ACCOUNTING & TAXATION ♦ Volume 2♦ Number 1 ♦ 2010



        MARKET CONCENTRATION MEASURES AND
          INVESTMENT DECISIONS IN MEXICAN
               MANUFACTURING FIRMS
                           Antonio Ruiz-Porras, University of Guadalajara
                           Celina López-Mateo, University of Guadalajara

                                               ABSTRACT

We study how different measures of market concentration explain investment decisions of Mexican
manufacturing firms. The Herfindahl-Hirschman Index is the traditional measure of market structure
concentration. The Dominance Index is a competition measure used by Mexican regulators. The
econometric assessments suggest that investment decisions of Mexican firms can be better explained by
the Dominance Index than by the Herfindahl-Hirschman Index. Thus our results suggest that the
Mexican Dominance Index might be useful as a measure of market structure and competition. The results
also suggest that market concentration reduces investment. These conclusions are based on several
econometric assessments.

JEL: L40; L22; L60

KEYWORDS: Dominance Index, Herfindahl-Hirschman Index, Investment, Mexico, Manufacturing

INTRODUCTION



T     raditional economic theory indicates that the maximization of profits explains the behavior and
      decisions of firms. Particularly, from the view of financial economics, firms are considered as
      flows of financial streams that depend on investments. Such view explains why the study of
optimal investment decisions and their determinants is considered an important research field for
economists.

Here we study the determinants of investment decisions in Mexican manufacturing firms because studies
for emerging economies are relatively scarce. Particularly, we focus on how market concentration, as a
proxy of market structure and competition, influences investment decisions. The assumption underlying
our study is that Mexican firms face constraints imposed by its competitors and by nature.

In the literature, competition constraints are analyzed with market concentration indexes. In this study we
follow this practice. The Herfindahl-Hirschman Index (HHI) is the usual measure of competition.
However it is not the only one. An alternative measure is the Dominance Index (DI) proposed by Garcia
Alba (1990). The main difference between these measures is that the DI explicitly accounts the size of
firms to measure competition.

We analyze how these two measures of market concentration may explain investment decisions of
Mexican manufacturing firms. We focus on micro, small, medium and large size firms. We control for
certain firm characteristics that capture the constraints that firms face by nature. They include firm size,
cash flow, capital intensity and investment opportunities.

The contributions of this research focus on two areas. The former contributions relate to the literature on
investment determinants. Traditional studies focus on developed economies, not in emerging ones. The
second contribution is methodological. To the best of our knowledge, econometric comparisons of the
HHI and the DI as market concentration measures do not exist.


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The paper is organized as follows. Section 2 reviews the literature. Section 3 describes the
methodological design: data, variables and model specification. Section 4 shows our regression results.
Section 5 discusses them in terms of their implications for economic policy. Section 6 concludes.

LITERATURE REVIEW AND BACKGROUND

Here we review the economic literature about firm investment decisions. The review follows the
guidelines of the Structure-Conduct-Performance (SCP) paradigm. We begin our review by describing
the concentration indexes analyzed in this investigation. Then we indicate some studies that have
analyzed the determinants of investment decisions on empirical and theoretical grounds.

Traditional industrial organization studies analyze firms under the basis of the SCP paradigm. This
paradigm explains firms´ decisions and their performance in terms of the notion of market structure. In
such studies, the Herfindahl-Hirschman Index (HHI) is the standard measure of market structure and
concentration.

The HHI measures market structure under the assumption that firms of a market are identical and that
competition is symmetric. Thus the HHI is an adequate measure of concentration and competition when
big differences do not exist among the firms. Methodologically, the index is measured as the inverse of
the number of firms. Its construction only takes into account the concentration of output.

The Dominance Index (DI) is a measure used by Mexican regulators since the nineties. Garcia Alba
(1990) developed it to assess how differences in firms´ size may affect the strategic interactions in the
market. In fact, the DI assesses the capacity of two o more small firms to compete against large firms.
Thus it is an index that considers how total output is allocated among the firms

Market concentration indexes have been subject to criticism under methodological basis. Particularly, Ten
Kate (2006) argues that the DI is a hybrid between a concentration index and an inequality index. He also
argues that changes in strategic interactions may not be properly taken into account with the index.
Moreover he argues that identical firms are not necessarily better competitors than different ones.

The relevance of the discussion regarding market concentration indexes is not only methodological.
Some theoretical studies explicitly suggest that market structure modifies the behavior of firms. The
paper of Akdoğu and MacKay (2006) is relevant for our purposes because they argue that investment
decisions depend on the strategic interactions prevailing in the markets. Moreover, in a later study they
confirm that investment depends inversely on industry concentration (Akdoğu and MacKay, 2008).

Empirical evidence is not conclusive. For example, Lee and Hwang (2003) do not find any relationships
between market structure determinants and investment decisions in the Korean telecommunication
industry. Indeed they conclude that market structure (measured by the HHI) is not a determinant of
Research and Development (R&D) investment. However, in another study Escrihuela-Villar (2008)
concludes that investment depends directly on market concentration.

Interestingly both studies, Lee and Hwang (2003) and Escrihuela-Villar (2008), indicate that certain
determinants are necessary to understand the relationships between market structure and investment.
Concretely, both studies indicate that firm size and investment opportunities determine investment
decisions. Particularly, Escrihuela-Villar (2008) finds that large firms invest more than small ones.

Evidence from developed economies confirms that further determinants are necessary to analyze the
relationships between market structure and investment. Mishra (2007) and Czarnitzk and Binz (2008)
find direct relationships among investment intensity, market structure and firm size. Bøhren, Cooper and


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Priestley (2007), D’Erasmo (2007) and Ughetto (2008), also find direct relationships among investment
decisions and cash flow, firm size and capital intensity. De Marzo and Fishman (2007) find that
investments for small and medium firms are sensitive to cash flows.

Empirical research on the relationships between market structure and investment for emerging economies
are limited. Existing studies mostly focus on other determinants of investment decisions. For example,
Adelegen and Ariyo (2008) and Bokpin and Onumah (2009) find that firm size, cash flow and investment
opportunities may explain investment decisions. The first study focuses on the Nigerian economy. The
second one analyses manufacturing firms in several emerging markets.

We emphasize that further studies are necessary to understand the relationships among market structure
and investment decisions in emerging economies. Here we propose an econometric analysis with the HHI
and DI measures of market concentration to analyze such relationships. We include some complementary
determinants according the findings of previous studies. The methodological issues and outcomes
regarding such analysis are described in the following sections.

METHODOLOGY

Here we describe the methodological design of the investigation. Specifically, we describe the sources of
data and the indicators used in the econometric assessments. Furthermore we describe the econometric
modeling and testing procedure used to analyze the relationships among market structure and investment
decisions in the Mexican manufacturing firms.

Data Sources

We use data from the “Economic Census 2003” reported by the Mexican Bureau of Statistics (INEGI).
Such census is constructed accordingly to the North-American-Industry-Classification-System (NAICS).
We use a longitudinal data set because data of previous censuses are built with non-comparable
methodologies. In Mexico census data are collected every five years. Currently, data for the census
collected in 2008 is not available.

In the census, firm-level data are not available due to confidentiality reasons. We deal with such
constraint by constructing a set of four representative firms for each of the 182 industries. We build the
representative firms accordingly to the number of employees. A micro firm has no more than 10
employees. A small firm has between 11 and 50. A medium firm has between 51 and 250. A large firm
has at least 251 employees. This classification follows the one of the Mexican Economics Ministry for
manufacturing firms.

The census classifies firms of each industry into groups according to the number of employees. For
example, the first group includes firms with 0 to 2 employees. The second group includes firms with 3 to
5, and so on. The census has 12 classificatory groups for each of the 182 industries. As we have
indicated, the Mexican Economics Ministry uses a different classification for the firms. Table 1 shows
the relationships between both classifications.

The first step to build a variable that describes the behavior for a representative firm of size j of industry i
is to calculate a weight indicator. We use the mean of the number of employees by group to calculate it.
This is calculated as follows:




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          n ijt M jt
Pijt =
         ∑n
         t
                 ijt M jt
                                                                                                                                          (1)
i = 1, ...,182
j = 1, 2, 3, 4
t = 1, ...,12


where Pijt is the weighted indicator of the industry i, size j, group t; nijt is the number of firms of the
industry i, size j, group t; Mjt is the mean of the number of employees of size j in group t; the subindex i
refers to the i-th industry; the subindex j refers to the firm of size j (micro, small, medium and large
firms); the subindex t refers to the t-th groups included in the size-j classification.

Table 1: The Census and the Mexican Economics Ministry Classifications for the Firms of an Industry

  Census´ Classification      Employees in the Firms       Mean of Employees in         Type of Firm According to           Firms´ Size
 of Firms in the Industry     that Belong to Group t       the Firms that Belong         the Mexican Economics            According to the
            i(t)                                              to Group t (Mjt)           Ministry´ classification         Type of Firm (j)

                1                           0-2                          1                               Micro                     1
                2                           3-5                          4                               Micro                     1
                3                           6-10                         8                               Micro                     1
                4                          11-15                        13                               Small                     2
                5                          16-20                        18                               Small                     2
                6                          21-30                        25                               Small                     2
                7                          31-50                        40                               Small                     2
                8                         51-100                        75                              Medium                     3
                9                         101-250                      175                              Medium                     3
               10                         251-500                      375                               Large                     4
               11                        501-1000                      750                               Large                     4
               12                          1000+                                                         Large                     4
This table shows the relationships between the Economic Census´ classification and the one of the Mexican Economics Ministry. The census
classifies firms of each industry into groups according to the number of employees. The census has 12 classificatory groups for each of the 182
industries. Mexican Economics Ministry´ classification for manufacturing firms considers four types. A micro firm has no more than 10
employees. A small firm has between 11 and 50. A medium firm has between 51 and 250. A large firm has at least 251 employees. The mean of
employees for the firms of the twelfth group is the average of employees with respect to the total of firms in the twelfth group.


The second step is to use the weighted indicator of each one of the four representative firms of industry i
to estimate each variable assessed econometrically. We multiply Pijt by each variable included in the
census classification for each one of the twelve groups of firms Vijt (see Table 2 for a list of variables).
Such multiplications added accordingly to each subindex t will provide us with a variable each
representative firm of size j of the industry i.

RFij =   ∑P  t
                 ijt Vijt


i = 1, ...,182                                                                                                                             (2)
j = 1, 2, 3, 4
t = 1, ...,12

where RFij is a variable associated to the representative firm of the industry i, size j; Pijt is the weighted
indicator of the industry i, size j, group t.




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Variables

Here we describe the main variables used in our study. We use the ones proposed by Bøhren, Cooper and
Priestley (2007) and Akdoğu and Mackay (2008). The variables used in the econometric assessments are
summarized in the following table:

Table 2: Investment and Its Determinants (Variables)

                  Variables                       Measures                      Indicator of the Census
 Investment                           Fixed capital expenditures           Gross fixed capital formation
                                                                           (Value of fixed assets bought
                                                                           during 2003 minus the value of
                                                                           fixed assets sales)

 Investment opportunities             Ratio of output to capital           Ratio of production value to fixed
                                                                           capital stock

 Market concentration                 Market concentration measures        Herfindhal-Hirschman Index
                                                                           Dominance Index

 Cash flow                            Earnings                             Net earnings

 Firm size                            Fixed assets                         Total value of fixed assets

 Capital intensity                    Ratio of capital to labor            Ratio of fixed capital stock to
                                                                           number of employees

This table shows the variables and indicators used in the econometric assessments. The dependent variable is investment. The other variables
are the independent variables used in this investigation. The table includes the definitions of the variables (indicators) according to the
Economic Census of INEGI (Mexican Bureau of Statistics).


The measures of market concentration are the HHI and the DI indexes. We do not build indexes for each
industry because certain groups of industries can be considered, for practical purposes, as competitors in
the same market. We deal with this fact by grouping the industries in subsectors. We estimate 21
subsector level measures of market concentration. We use the total number of firms that belong to each
group of industries to build the measure that corresponds to each subsector.

The measure of market concentration assumes that all the firms in a subsector are in the same market.
Under that assumption, we define the HHI as follows:

              n
HHI s =      ∑m
             k =1
                      2
                      ks                                                                                                                (3)


where mks represents the share of the firm k in the total product of the subsector s; n is the number of
firms in the subsector s.
The Dominance Index is estimated in the same way as the HHI. Firms using similar raw material inputs,
similar capital equipment, and similar labor are classified in the same subsector. Thus, we estimate again
21 subsector level measures of market concentration. Again, the measure of market concentration
assumes that all the firms in a subsector are in the same market. Under that assumption, we define the DI
as:

DI s =   ∑M         ts Yts                                                                                                              (4)

where Mts is the share of the production of the group t in the production of the subsector s; Yts is the firm
average production of the group t, subsector s.


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Modeling Specification and Econometric Techniques

We use a log-linear functional form specification to describe the relationships between market structure
and investment. Such specification allows the regression coefficients to measure the elasticity of
investment with respect to each independent variable (determinant). Moreover, the log transformation
reduces the possibility of heteroscedasticity problems. Thus the model specification is:

ln I ij = α 0 + α1 ln IOij + α 2 ln CFij + α 3 ln Sij + α 4 ln MC ij + α 5 ln KI ij + ε ij                                               (5)

where Iij is investment; IOij represents the investment opportunities; CFij is cash flow; Sij is the size of the
firm; MCij is the market concentration; KIij represents the capital intensity; eij is the random error term.

The analysis relies on several estimations of the equation (5). Concretely it relies on two sets of
regressions. The first set includes estimations that use the HHI index as measure of market concentration.
The second set uses estimations with the DI index. Each set is conformed by four regressions that assess
how market concentration relates to investment for firms of a specific size (micro, small, medium and
large). We use Ordinary Least Squares (OLS) for estimation purposes in both sets of regressions. In
addition, we use specification-error Ramsey tests. The tests allow us to validate the econometric
assumptions regarding the functional specification form and to detect omitted-variable bias.

EMPIRICAL ASSESSMENT

Table 3 reports the summary of descriptive statistics of the variables. The variable means seem to depend
on the size of the firms. The means associated to micro firms are smaller than the ones of small firms.
The means associated to medium firms are smaller than the ones of large firms. These facts support the
necessity to differentiate firms by size.

Table 3: Summary Statistics

                                           Std.                                            Std.
                          Obs     Mean     Dev.      Min.       Max.      Obs     Mean     Dev.    Min.          Max.
       Variables                         Micro firms                                    Medium firms
  Investment               118     16.66   5.61      3.82        31.48     147    16.91    3.44     5.29         24.98
  Cash flow                118     28.28   5.24      9.11        42.73     147    24.53    3.39     8.67         30.90
  Firm size                118     26.45   5.01      12.76       40.00     147    22.79    3.40     7.48         31.60
  Capital intensity        118       8.86  1.77      0.16        13.65     147     8.51    1.86     3.32         16.52
  Investment
  opportunities            118      -2.09    1.75     -14.01      1.11     147      0.24       1.17     -4.28     2.97
  HHI                      118      -5.65    0.77      -6.74     -2.04     147     -5.45       0.87     -6.74    -2.04
  DI                       118      -3.21    1.01      -5.35     -1.11     147     -3.16       1.10     -5.35    -1.11
       Variables                           Small firms                                      Large firms
  Investment               107     24.10     6.18       5.25     38.00     118     22.04       8.57      5.86    37.63
  Cash flow                107     40.43     5.67      10.04     51.46     118     31.04       11.11    10.32    47.82
  Firm size                107     36.32     5.76       6.51     49.51     118     29.07       10.46     9.44    44.52
  Capital intensity        107     12.42     2.44       3.17     21.33     118     10.32       3.72      3.14    19.97
  Investment
  opportunities            107      -1.82    1.60      -5.07      3.53     118     -0.46       1.87     -4.63     3.86
  HHI                      107      -5.53    0.92      -6.74     -2.04     118     -5.47       0.89     -6.74    -2.04
  DI                       107      -3.17    1.05      -5.35     -1.11     118     -3.28       1.14     -5.35    -1.16
This table shows summary statistics. It presents measures of central tendency. Also, this table shows the independent and dependent variables
used in model specification. The dependent variable is investment. Summary statistics is presented for micro, small, medium and large firms.
Values are expressed in natural logarithms.


Table 4 reports the regression outcomes for the first set of regressions. Apparently, the HHI coefficient is
positive and significant only for micro firms. Firm size coefficients are positive and significant,
independently of the type of firm. In most cases, the coefficients associated to cash flows and investment


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opportunities are significant. Investment opportunities and firm size coefficients are positive and
significant for small firms. The cash flow coefficient is negatively correlated with investment decisions
and is statistically significant. Medium and large firms show similar patterns. In all cases, the results
show high values of R2. In addition, the joint significance F tests suggest that the independent variables
are necessary to explain investment decisions.

Table 4: HHI Concentration Measures and Investment Decisions in Mexican Manufacturing Firms (OLS
Regressions)

                     Firm Size                             Micro             Small            Medium             Large
                                                  Regression indicators
  Investment opportunities                                    0.39         1.91***             1.55***          1.60***
                                                            (1.14)           (5.36)              (3.56)           (4.86)
  Herfindahl- Hirschman Index (HHI)                       0.67***             0.24              -0.056             -7.50
                                                            (2.98)           (0.92)             (-0.35)          (-0.70)
  Cash flow                                                  -0.40         -1.62***           -1.27***         -1.16***
                                                           (-1.21)          (-4.60)             (-2.90)          (-3.55)
  Firm size                                               1.47***          2.70***             2.26***          2.15***
                                                            (4.63)           (7.44)              (4.75)           (5.61)
  Capital intensity                                           0.02            -0.06               0.02              0.02
                                                            (0.24)          (-0.44)              (0.19)           (0.18)
  Constant                                               -6.57***             -2.84           -4.11***         -3.76***
                                                           (-2.69)          (-1.09)             (-3.45)          (-4.91)
  Observations                                                118              107                147               118
  F                                                     225.16***         134.10***          109.58***        444.44***
  Prob > F                                                    0.00             0.00               0.00              0.00
  R2                                                          0.91            0.86                0.79              0.95
This table reports results for OLS regressions. They use the Herfindahl- Hirschman Index as a proxy of market structure. The dependent
variable is investment. The results are presented for firm size. The t-statistics are given in parenthesis. ***, **, and * indicate significance at
the 1, 5 and 10 percent levels respectively.


Table 5 reports the regression outcomes for the second set of regressions. Here we find that the DI
coefficient is a negative and statistically significant for medium and large firms. The coefficients
associated to investment opportunities are positive and significant in most cases. Cash flow coefficients
are negative and statistically significant. The coefficients associated to firm size are positive and
significant in all cases.

Table 5: DI Concentration Measures and Investment Decisions in Mexican Manufacturing Firms (OLS
Regressions)

                Firm size                        Micro                 Small              Medium                 Large
                                                    Regression Indicators
  Investment opportunities                         0.17               1.87***              1.68***              1.57***
                                                  (0.49)                (5.23)               (3.83)               (4.80)
  Dominance Index (DI)                             0.11                  -0.04              -0.20*               -4.43*
                                                  (0.62)               (-0.19)              (-1.66)              (-1.82)
  Cash flow                                        -0.21              -1.58***            -1.41***             -1.15***
                                                 (-0.64)               (-4.48)              (-3.18)              (-3.57)
  Firm size                                     1.27***               2.64***              2.40***              2.13***
                                                  (3.92)                (7.35)               (5.01)               (5.63)
  Capital intensity                                0.17                  -0.03                0.02                 0.05
                                                  (0.49)               (-0.24)               (0.18)               (0.50)
  Constant                                     -10.50***               -4.34*             -4.42***             -3.53***
                                                 (-4.82)               (-1.81)              (-4.38)              (-4.62)
  Observations                                      118                   107                 147                  118
  F                                            207.74***             132.86***           112.14***            456.12***
  Prob > F                                         0.00                  0.00                 0.00                 0.00
  R2                                               0.90                  0.86                 0.79                 0.95
This table reports results for OLS regressions. They use the Dominance Index as a proxy of market structure. The dependent variable is
investment. The results are presented for firm size. The t-statistics are given in parenthesis. ***, **, and * indicate significance at the 1, 5 and
10 percent levels respectively.




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Like in the previous set of regressions, the results show high values of R2. Such values confirm that the
explanatory variables can explain investment decisions. Again the F tests confirm that the set of
independent variables explains them. So, apparently both sets of regression may provide similar
information. The only exception relies on the positive and significant coefficient associated to the market
concentration variable for micro firms in the first set of regressions.

We support the robustness of our previous results with specification-error Ramsey tests. Such tests allow
us to deal with the differences of information. Here we use two versions of the Ramsey test. The first
one, the traditional RESET test, uses powers of the estimated independent variable as regressors. The
second one uses powers of the RHS variables. The null hypothesis is that the model is adequately
specified in both versions of the test.

The outcomes of the tests of both sets of regressions suggest that the econometric assessments for small,
medium and large firms do not have specification errors. The modeled relationships between market
concentration and investment decisions seem adequate in most cases. However, the exception is referred
to micro firms. For these firms, the regressions suggest the existence of omitted variable-bias and/or
incorrect functional forms.

The Ramsey tests suggest that the differences reported between the two sets of regressions should not be
considered relevant. In fact, the comparison of the reported outcomes and tests suggest that the
regressions that include the DI index might be better than the ones that include the HHI index. We
support this statement on the basis that the only significant coefficients associated to the concentration
variables appear in the second set of regressions (see Table 5). As we have indicated, the regression of
the first set associated to the micro firms has specification errors (see Tables 4 and 6).

Here is important to point out that the outcomes suggest that how market concentration affects investment
decisions depends on the size of the firms. According to the regressions with the DI index, it seems that
concentration significantly reduces investment for medium and large size firms. When firms are micro or
small ones, the evidence is not conclusive due to specification errors and non significant variables (see
Table 5).

Table 6: Model Validation (Specification Tests)

                         Firm size                               Micro           Small          Medium            Large

                                   Models with Herfindhal-Hirschaman Index (HHI)
  Ramsey test
  (H0: Model has no specification error)                    7.06***       0.85                    2.24*            0.82
  Prob > F                                                   0.0002      0.4720                  0.0859           0.4875
  Ramsey test, rhs
  (H0: model has no omitted variables)                      2.66***       0.76                    0.80             0.81
  Prob > F                                                   0.0020      0.7197                  0.6788           0.6655

                                             Models with Dominance Index (DI)
  Ramsey test
  (H0: model has no omitted variables                              7.68***           0.90           2.35*            0.43
  Prob > F                                                          0.0001          0.4465         0.0750           0.7287
  Ramsey test, rhs
  (H0: model has no omitted variables)                             2.84***           0.75            0.74            0.66
  Prob > F                                                          0.0011          0.7295         0.7434           0.8123
This table shows results of Ramsey test. It is used to detect specification errors. This table shows two versions of the of the Ramsey test. Ramsey
test (rhs) uses powers of the independent variables. Instead Ramsey test uses powers of the fitted values of the dependent variable. ***, **, and
* indicate significance at the 1, 5 and 10 percent levels respectively.


We conclude by indicating that the evidence supports the view that market concentration reduces
investment, at least in medium and large firms. Thus, according to our results, competition may promote


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investment. Furthermore the evidence provides elements to support the statistical adequacy of the DI
index as an adequate measure of market concentration. Moreover, the results suggest that the regressions
that include the DI index might be better than the ones that include the HHI index.

DISCUSSION

Here we have assessed the relationships between market structure and investment decisions in the
Mexican manufacturing firms. The assessments suggest that market concentration may reduce
investment, at least in medium and large firms. Thus, competition may promote investment.
Furthermore, they confirm that certain firm characteristics may be useful to explain investment decisions.
Particularly, firm size seems an important determinant.

However, it is interesting to point out that some findings seem counter intuitive. For example, capital
seems not to influence investment decisions. Furthermore, cash flows seem to have an inverse
relationship with investment. We believe that such findings may be explained on the basis that
manufacturing firms are intensive in labor. When firms are labor-intensive, investments may rely on new
“costly” workers that reduce cash flows.

Methodologically, the assessment procedure seems useful to explain the investment decisions of small,
medium and large firms. Furthermore, it supports the hypothesis that investment decisions in micro firms
may depend on other determinants, in addition to the market structure ones. Ekanem and Smallbone
(2007) include, among these determinants, the intuition, the social networks and the experience of the
entrepreneurs.

Empirically, we believe that the most interesting findings relate to the usefulness of the different market
concentration measures. Our econometric assessment suggests that the Dominance Index (DI) is a better
determinant of investment decisions than the Herfindahl-Hirschman Index (HHI). In practice, this finding
implies that the degree of competition can affected by differences in the size of the firms in the market.
Thus regulators may need to consider these differences when dealing with competition issues.

We conclude by indicating that our findings have implications for regulatory and policy purposes.
Probably, the most important one is associated to the necessity to promote the Dominance Index as an
alternative measure of market competition. Another one relates to the necessity to encourage competition
among the Mexican firms in order to increase investment. Finally, a third one relates to the necessity to
encourage studies on the determinants of investment in micro and small size firms because our evidence
is not conclusive.

CONCLUSIONS

We have studied how alternative measures of market concentration, as proxy indicator of market
structure, may explain investment decisions of Mexican manufacturing firms. Here we have focused on
the HHI and the DI measures. We have developed an econometric analysis that uses data for the last
census available in Mexico (2003). We have controlled by firm size, cash flow, capital intensity and
investment opportunities.

Methodologically, the empirical study has relied on two regression sets. The first set includes estimations
that use the HHI index as measure of market concentration. The second one includes estimations that use
the DI index. We have used OLS techniques for estimation purposes. In addition, we have used Ramsey
tests to validate the econometric outcomes. We have used data of the census to build the indicators of the
182 industries that integrate the Mexican manufacturing sector.



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Our findings confirm that market structure may influence investment decisions. Concretely they suggest
that concentration may reduce investment. Thus they confirm the findings of Akdoğu and MacKay
(2008). Our findings also suggest that the DI index is a better determinant than the HHI one.
Furthermore, they suggest that firm size and investment opportunities have a direct relationship with
investment. Cash flows, on the other hand, have an inverse one. Interestingly, capital intensity is not
related to investment decisions.

We believe that our study provides some ideas for further research. For example, extensions of our
analysis could be used to analyze investment decisions in firms that provide financial and non-financial
services. The “Economic Census 2008”, when available, may provide data useful for comparison
purposes. Finally, our results also suggest that further studies on the determinants of investments in micro
and small firms may be necessary.

REFERENCES

Adelegan, O.A. & Ariyo, A. (2008) “Capital Market Imperfections and Corporate Investment Behavior:
A Switching Regression Approach Using Panel Data for Nigerian Manufacturing Firms”, Journal of
Money, Investment and Banking, vol. 2, March, p. 16-38

Akdoğu, E. & MacKay, P. (2006) “Externalities and Corporate Investment”, Working Paper Series,
February, p. 1-39

______ (2008) “Investment and Competition”, Journal of Financial and Quantitative Analysis, vol. 43(2),
June, p. 299-330
Bøhren, Ø., Cooper, I. & Priestley, R. (2007) “Corporate Governance and Real Investment Decisions”,
European Finance Association, Working Paper, March, p. 1-29

Bokpin, G.A. & Onumah, J.M. (2009) “An Empirical Analysis of the Determinants of Corporate
Investment Decisions: Evidence from Emerging Market Firms”, International Research Journal of
Finance and Economics, vol. 33, November, p. 134-141

Czarnitzk, D. & Binz, H.L. (2008) “R&D Investment and Financing Constraints of Small and Medium-
Sized Firms”, Discussion Paper No. 08-047, Centre for European Economic Research, p. 1-28

D'Erasmo, P. (2007) “Investment and Firm Dynamics”, Working Paper, University of Texas at Austin,
July, p. 1-33

DeMarzo, P.M. & Fishman, M.J. (2007) “Agency and Optimal Investment Dynamics”, The Review of
Financial Studies, Oxford Journals, vol. 20, January, p. 151-188

Ekanem, I. & Smallbone, D. (2007) “Learning in Small Manufacturing Firms. The Case of Investment
Decision Making Behavior”, International Small Business Journal, vol. 25(2), April, p. 107-129

Escrihuela-Villar, M. (2008) “Innovation and Market Concentration with Asymmetric Firms”, Economics
of Innovation and New Technology, vol. 17(3), p. 195-207

García Alba Iduñate, P. (1990) “Un Enfoque para Medir la Concentración Industrial y su Aplicación al
Caso de México”, El Trimestre Económico, vol. LVII (226), Abril-Junio, FCE, México, p. 317-341

Lee, M.H. & Hwang, I.J. (2003) “Determinants of Corporate R&D Investment: An Empirical Study
Comparing Korea’s IT Industry with Its Non-IT Industry”, ETRI Journal, vol. 25(4), August, p. 258-265


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ACCOUNTING & TAXATION ♦ Volume 2♦ Number 1 ♦ 2010



Mishra, V. (2007) “The Determinants of R&D Expenditure of Firms: Evidence from a Cross-Section of
Indian firms”, Economic Papers, vol. 26(3), September, Economic Society of Australia, p. 237-248

Ten Kate, A. (2006) “The Dominance Index in Mexican Merger Control: Does it Perform Better than the
HHI?”, The Antitrust Bulletin, vol. 51(2), Summer, p. 383-409

Ughetto, E. (2008) “Does internal finance matter for R&D? New evidence from a panel of Italian firms”,
Cambridge Journal of Economics, vol. 32(6), April, p. 907-925

BIOGRAPHY

Antonio Ruiz-Porras is professor and researcher in the Department of Quantitative Methods at the
University of Guadalajara. Address for correspondence: Departamento de Métodos Cuantitativos.
Universidad de Guadalajara, CUCEA. Periférico Norte 799. Núcleo Universitario Los Belenes, 45140.
Zapopan, Jalisco, México. Telephone: ++ (52) (33) 3770 3300 ext. 5291. Fax: ++ (52) (33) 3770 3300
ext. 5227. Email: antoniop@cucea.udg.mx

Celina López-Mateo is student in the Doctoral Program of Economic and Managerial Sciences at the
University of Guadalajara. Address for correspondence: Programa Doctoral en Ciencias Económico-
Administrativas. Universidad de Guadalajara, CUCEA. Periférico Norte 799. Núcleo Universitario Los
Belenes, 45140. Zapopan, Jalisco, México. Email: celinalm@gmail.com




                                                                                                   69

Market concentration measures and investment decisions in mexican manufacturing firms

  • 1.
    ACCOUNTING & TAXATION♦ Volume 2♦ Number 1 ♦ 2010 MARKET CONCENTRATION MEASURES AND INVESTMENT DECISIONS IN MEXICAN MANUFACTURING FIRMS Antonio Ruiz-Porras, University of Guadalajara Celina López-Mateo, University of Guadalajara ABSTRACT We study how different measures of market concentration explain investment decisions of Mexican manufacturing firms. The Herfindahl-Hirschman Index is the traditional measure of market structure concentration. The Dominance Index is a competition measure used by Mexican regulators. The econometric assessments suggest that investment decisions of Mexican firms can be better explained by the Dominance Index than by the Herfindahl-Hirschman Index. Thus our results suggest that the Mexican Dominance Index might be useful as a measure of market structure and competition. The results also suggest that market concentration reduces investment. These conclusions are based on several econometric assessments. JEL: L40; L22; L60 KEYWORDS: Dominance Index, Herfindahl-Hirschman Index, Investment, Mexico, Manufacturing INTRODUCTION T raditional economic theory indicates that the maximization of profits explains the behavior and decisions of firms. Particularly, from the view of financial economics, firms are considered as flows of financial streams that depend on investments. Such view explains why the study of optimal investment decisions and their determinants is considered an important research field for economists. Here we study the determinants of investment decisions in Mexican manufacturing firms because studies for emerging economies are relatively scarce. Particularly, we focus on how market concentration, as a proxy of market structure and competition, influences investment decisions. The assumption underlying our study is that Mexican firms face constraints imposed by its competitors and by nature. In the literature, competition constraints are analyzed with market concentration indexes. In this study we follow this practice. The Herfindahl-Hirschman Index (HHI) is the usual measure of competition. However it is not the only one. An alternative measure is the Dominance Index (DI) proposed by Garcia Alba (1990). The main difference between these measures is that the DI explicitly accounts the size of firms to measure competition. We analyze how these two measures of market concentration may explain investment decisions of Mexican manufacturing firms. We focus on micro, small, medium and large size firms. We control for certain firm characteristics that capture the constraints that firms face by nature. They include firm size, cash flow, capital intensity and investment opportunities. The contributions of this research focus on two areas. The former contributions relate to the literature on investment determinants. Traditional studies focus on developed economies, not in emerging ones. The second contribution is methodological. To the best of our knowledge, econometric comparisons of the HHI and the DI as market concentration measures do not exist. 59
  • 2.
    A. Ruiz-Porras, C.López-Mateo | AT ♦ Vol. 2 ♦ No. 1 ♦ 2010 The paper is organized as follows. Section 2 reviews the literature. Section 3 describes the methodological design: data, variables and model specification. Section 4 shows our regression results. Section 5 discusses them in terms of their implications for economic policy. Section 6 concludes. LITERATURE REVIEW AND BACKGROUND Here we review the economic literature about firm investment decisions. The review follows the guidelines of the Structure-Conduct-Performance (SCP) paradigm. We begin our review by describing the concentration indexes analyzed in this investigation. Then we indicate some studies that have analyzed the determinants of investment decisions on empirical and theoretical grounds. Traditional industrial organization studies analyze firms under the basis of the SCP paradigm. This paradigm explains firms´ decisions and their performance in terms of the notion of market structure. In such studies, the Herfindahl-Hirschman Index (HHI) is the standard measure of market structure and concentration. The HHI measures market structure under the assumption that firms of a market are identical and that competition is symmetric. Thus the HHI is an adequate measure of concentration and competition when big differences do not exist among the firms. Methodologically, the index is measured as the inverse of the number of firms. Its construction only takes into account the concentration of output. The Dominance Index (DI) is a measure used by Mexican regulators since the nineties. Garcia Alba (1990) developed it to assess how differences in firms´ size may affect the strategic interactions in the market. In fact, the DI assesses the capacity of two o more small firms to compete against large firms. Thus it is an index that considers how total output is allocated among the firms Market concentration indexes have been subject to criticism under methodological basis. Particularly, Ten Kate (2006) argues that the DI is a hybrid between a concentration index and an inequality index. He also argues that changes in strategic interactions may not be properly taken into account with the index. Moreover he argues that identical firms are not necessarily better competitors than different ones. The relevance of the discussion regarding market concentration indexes is not only methodological. Some theoretical studies explicitly suggest that market structure modifies the behavior of firms. The paper of Akdoğu and MacKay (2006) is relevant for our purposes because they argue that investment decisions depend on the strategic interactions prevailing in the markets. Moreover, in a later study they confirm that investment depends inversely on industry concentration (Akdoğu and MacKay, 2008). Empirical evidence is not conclusive. For example, Lee and Hwang (2003) do not find any relationships between market structure determinants and investment decisions in the Korean telecommunication industry. Indeed they conclude that market structure (measured by the HHI) is not a determinant of Research and Development (R&D) investment. However, in another study Escrihuela-Villar (2008) concludes that investment depends directly on market concentration. Interestingly both studies, Lee and Hwang (2003) and Escrihuela-Villar (2008), indicate that certain determinants are necessary to understand the relationships between market structure and investment. Concretely, both studies indicate that firm size and investment opportunities determine investment decisions. Particularly, Escrihuela-Villar (2008) finds that large firms invest more than small ones. Evidence from developed economies confirms that further determinants are necessary to analyze the relationships between market structure and investment. Mishra (2007) and Czarnitzk and Binz (2008) find direct relationships among investment intensity, market structure and firm size. Bøhren, Cooper and 60
  • 3.
    ACCOUNTING & TAXATION♦ Volume 2♦ Number 1 ♦ 2010 Priestley (2007), D’Erasmo (2007) and Ughetto (2008), also find direct relationships among investment decisions and cash flow, firm size and capital intensity. De Marzo and Fishman (2007) find that investments for small and medium firms are sensitive to cash flows. Empirical research on the relationships between market structure and investment for emerging economies are limited. Existing studies mostly focus on other determinants of investment decisions. For example, Adelegen and Ariyo (2008) and Bokpin and Onumah (2009) find that firm size, cash flow and investment opportunities may explain investment decisions. The first study focuses on the Nigerian economy. The second one analyses manufacturing firms in several emerging markets. We emphasize that further studies are necessary to understand the relationships among market structure and investment decisions in emerging economies. Here we propose an econometric analysis with the HHI and DI measures of market concentration to analyze such relationships. We include some complementary determinants according the findings of previous studies. The methodological issues and outcomes regarding such analysis are described in the following sections. METHODOLOGY Here we describe the methodological design of the investigation. Specifically, we describe the sources of data and the indicators used in the econometric assessments. Furthermore we describe the econometric modeling and testing procedure used to analyze the relationships among market structure and investment decisions in the Mexican manufacturing firms. Data Sources We use data from the “Economic Census 2003” reported by the Mexican Bureau of Statistics (INEGI). Such census is constructed accordingly to the North-American-Industry-Classification-System (NAICS). We use a longitudinal data set because data of previous censuses are built with non-comparable methodologies. In Mexico census data are collected every five years. Currently, data for the census collected in 2008 is not available. In the census, firm-level data are not available due to confidentiality reasons. We deal with such constraint by constructing a set of four representative firms for each of the 182 industries. We build the representative firms accordingly to the number of employees. A micro firm has no more than 10 employees. A small firm has between 11 and 50. A medium firm has between 51 and 250. A large firm has at least 251 employees. This classification follows the one of the Mexican Economics Ministry for manufacturing firms. The census classifies firms of each industry into groups according to the number of employees. For example, the first group includes firms with 0 to 2 employees. The second group includes firms with 3 to 5, and so on. The census has 12 classificatory groups for each of the 182 industries. As we have indicated, the Mexican Economics Ministry uses a different classification for the firms. Table 1 shows the relationships between both classifications. The first step to build a variable that describes the behavior for a representative firm of size j of industry i is to calculate a weight indicator. We use the mean of the number of employees by group to calculate it. This is calculated as follows: 61
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    A. Ruiz-Porras, C.López-Mateo | AT ♦ Vol. 2 ♦ No. 1 ♦ 2010 n ijt M jt Pijt = ∑n t ijt M jt (1) i = 1, ...,182 j = 1, 2, 3, 4 t = 1, ...,12 where Pijt is the weighted indicator of the industry i, size j, group t; nijt is the number of firms of the industry i, size j, group t; Mjt is the mean of the number of employees of size j in group t; the subindex i refers to the i-th industry; the subindex j refers to the firm of size j (micro, small, medium and large firms); the subindex t refers to the t-th groups included in the size-j classification. Table 1: The Census and the Mexican Economics Ministry Classifications for the Firms of an Industry Census´ Classification Employees in the Firms Mean of Employees in Type of Firm According to Firms´ Size of Firms in the Industry that Belong to Group t the Firms that Belong the Mexican Economics According to the i(t) to Group t (Mjt) Ministry´ classification Type of Firm (j) 1 0-2 1 Micro 1 2 3-5 4 Micro 1 3 6-10 8 Micro 1 4 11-15 13 Small 2 5 16-20 18 Small 2 6 21-30 25 Small 2 7 31-50 40 Small 2 8 51-100 75 Medium 3 9 101-250 175 Medium 3 10 251-500 375 Large 4 11 501-1000 750 Large 4 12 1000+ Large 4 This table shows the relationships between the Economic Census´ classification and the one of the Mexican Economics Ministry. The census classifies firms of each industry into groups according to the number of employees. The census has 12 classificatory groups for each of the 182 industries. Mexican Economics Ministry´ classification for manufacturing firms considers four types. A micro firm has no more than 10 employees. A small firm has between 11 and 50. A medium firm has between 51 and 250. A large firm has at least 251 employees. The mean of employees for the firms of the twelfth group is the average of employees with respect to the total of firms in the twelfth group. The second step is to use the weighted indicator of each one of the four representative firms of industry i to estimate each variable assessed econometrically. We multiply Pijt by each variable included in the census classification for each one of the twelve groups of firms Vijt (see Table 2 for a list of variables). Such multiplications added accordingly to each subindex t will provide us with a variable each representative firm of size j of the industry i. RFij = ∑P t ijt Vijt i = 1, ...,182 (2) j = 1, 2, 3, 4 t = 1, ...,12 where RFij is a variable associated to the representative firm of the industry i, size j; Pijt is the weighted indicator of the industry i, size j, group t. 62
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    ACCOUNTING & TAXATION♦ Volume 2♦ Number 1 ♦ 2010 Variables Here we describe the main variables used in our study. We use the ones proposed by Bøhren, Cooper and Priestley (2007) and Akdoğu and Mackay (2008). The variables used in the econometric assessments are summarized in the following table: Table 2: Investment and Its Determinants (Variables) Variables Measures Indicator of the Census Investment Fixed capital expenditures Gross fixed capital formation (Value of fixed assets bought during 2003 minus the value of fixed assets sales) Investment opportunities Ratio of output to capital Ratio of production value to fixed capital stock Market concentration Market concentration measures Herfindhal-Hirschman Index Dominance Index Cash flow Earnings Net earnings Firm size Fixed assets Total value of fixed assets Capital intensity Ratio of capital to labor Ratio of fixed capital stock to number of employees This table shows the variables and indicators used in the econometric assessments. The dependent variable is investment. The other variables are the independent variables used in this investigation. The table includes the definitions of the variables (indicators) according to the Economic Census of INEGI (Mexican Bureau of Statistics). The measures of market concentration are the HHI and the DI indexes. We do not build indexes for each industry because certain groups of industries can be considered, for practical purposes, as competitors in the same market. We deal with this fact by grouping the industries in subsectors. We estimate 21 subsector level measures of market concentration. We use the total number of firms that belong to each group of industries to build the measure that corresponds to each subsector. The measure of market concentration assumes that all the firms in a subsector are in the same market. Under that assumption, we define the HHI as follows: n HHI s = ∑m k =1 2 ks (3) where mks represents the share of the firm k in the total product of the subsector s; n is the number of firms in the subsector s. The Dominance Index is estimated in the same way as the HHI. Firms using similar raw material inputs, similar capital equipment, and similar labor are classified in the same subsector. Thus, we estimate again 21 subsector level measures of market concentration. Again, the measure of market concentration assumes that all the firms in a subsector are in the same market. Under that assumption, we define the DI as: DI s = ∑M ts Yts (4) where Mts is the share of the production of the group t in the production of the subsector s; Yts is the firm average production of the group t, subsector s. 63
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    A. Ruiz-Porras, C.López-Mateo | AT ♦ Vol. 2 ♦ No. 1 ♦ 2010 Modeling Specification and Econometric Techniques We use a log-linear functional form specification to describe the relationships between market structure and investment. Such specification allows the regression coefficients to measure the elasticity of investment with respect to each independent variable (determinant). Moreover, the log transformation reduces the possibility of heteroscedasticity problems. Thus the model specification is: ln I ij = α 0 + α1 ln IOij + α 2 ln CFij + α 3 ln Sij + α 4 ln MC ij + α 5 ln KI ij + ε ij (5) where Iij is investment; IOij represents the investment opportunities; CFij is cash flow; Sij is the size of the firm; MCij is the market concentration; KIij represents the capital intensity; eij is the random error term. The analysis relies on several estimations of the equation (5). Concretely it relies on two sets of regressions. The first set includes estimations that use the HHI index as measure of market concentration. The second set uses estimations with the DI index. Each set is conformed by four regressions that assess how market concentration relates to investment for firms of a specific size (micro, small, medium and large). We use Ordinary Least Squares (OLS) for estimation purposes in both sets of regressions. In addition, we use specification-error Ramsey tests. The tests allow us to validate the econometric assumptions regarding the functional specification form and to detect omitted-variable bias. EMPIRICAL ASSESSMENT Table 3 reports the summary of descriptive statistics of the variables. The variable means seem to depend on the size of the firms. The means associated to micro firms are smaller than the ones of small firms. The means associated to medium firms are smaller than the ones of large firms. These facts support the necessity to differentiate firms by size. Table 3: Summary Statistics Std. Std. Obs Mean Dev. Min. Max. Obs Mean Dev. Min. Max. Variables Micro firms Medium firms Investment 118 16.66 5.61 3.82 31.48 147 16.91 3.44 5.29 24.98 Cash flow 118 28.28 5.24 9.11 42.73 147 24.53 3.39 8.67 30.90 Firm size 118 26.45 5.01 12.76 40.00 147 22.79 3.40 7.48 31.60 Capital intensity 118 8.86 1.77 0.16 13.65 147 8.51 1.86 3.32 16.52 Investment opportunities 118 -2.09 1.75 -14.01 1.11 147 0.24 1.17 -4.28 2.97 HHI 118 -5.65 0.77 -6.74 -2.04 147 -5.45 0.87 -6.74 -2.04 DI 118 -3.21 1.01 -5.35 -1.11 147 -3.16 1.10 -5.35 -1.11 Variables Small firms Large firms Investment 107 24.10 6.18 5.25 38.00 118 22.04 8.57 5.86 37.63 Cash flow 107 40.43 5.67 10.04 51.46 118 31.04 11.11 10.32 47.82 Firm size 107 36.32 5.76 6.51 49.51 118 29.07 10.46 9.44 44.52 Capital intensity 107 12.42 2.44 3.17 21.33 118 10.32 3.72 3.14 19.97 Investment opportunities 107 -1.82 1.60 -5.07 3.53 118 -0.46 1.87 -4.63 3.86 HHI 107 -5.53 0.92 -6.74 -2.04 118 -5.47 0.89 -6.74 -2.04 DI 107 -3.17 1.05 -5.35 -1.11 118 -3.28 1.14 -5.35 -1.16 This table shows summary statistics. It presents measures of central tendency. Also, this table shows the independent and dependent variables used in model specification. The dependent variable is investment. Summary statistics is presented for micro, small, medium and large firms. Values are expressed in natural logarithms. Table 4 reports the regression outcomes for the first set of regressions. Apparently, the HHI coefficient is positive and significant only for micro firms. Firm size coefficients are positive and significant, independently of the type of firm. In most cases, the coefficients associated to cash flows and investment 64
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    ACCOUNTING & TAXATION♦ Volume 2♦ Number 1 ♦ 2010 opportunities are significant. Investment opportunities and firm size coefficients are positive and significant for small firms. The cash flow coefficient is negatively correlated with investment decisions and is statistically significant. Medium and large firms show similar patterns. In all cases, the results show high values of R2. In addition, the joint significance F tests suggest that the independent variables are necessary to explain investment decisions. Table 4: HHI Concentration Measures and Investment Decisions in Mexican Manufacturing Firms (OLS Regressions) Firm Size Micro Small Medium Large Regression indicators Investment opportunities 0.39 1.91*** 1.55*** 1.60*** (1.14) (5.36) (3.56) (4.86) Herfindahl- Hirschman Index (HHI) 0.67*** 0.24 -0.056 -7.50 (2.98) (0.92) (-0.35) (-0.70) Cash flow -0.40 -1.62*** -1.27*** -1.16*** (-1.21) (-4.60) (-2.90) (-3.55) Firm size 1.47*** 2.70*** 2.26*** 2.15*** (4.63) (7.44) (4.75) (5.61) Capital intensity 0.02 -0.06 0.02 0.02 (0.24) (-0.44) (0.19) (0.18) Constant -6.57*** -2.84 -4.11*** -3.76*** (-2.69) (-1.09) (-3.45) (-4.91) Observations 118 107 147 118 F 225.16*** 134.10*** 109.58*** 444.44*** Prob > F 0.00 0.00 0.00 0.00 R2 0.91 0.86 0.79 0.95 This table reports results for OLS regressions. They use the Herfindahl- Hirschman Index as a proxy of market structure. The dependent variable is investment. The results are presented for firm size. The t-statistics are given in parenthesis. ***, **, and * indicate significance at the 1, 5 and 10 percent levels respectively. Table 5 reports the regression outcomes for the second set of regressions. Here we find that the DI coefficient is a negative and statistically significant for medium and large firms. The coefficients associated to investment opportunities are positive and significant in most cases. Cash flow coefficients are negative and statistically significant. The coefficients associated to firm size are positive and significant in all cases. Table 5: DI Concentration Measures and Investment Decisions in Mexican Manufacturing Firms (OLS Regressions) Firm size Micro Small Medium Large Regression Indicators Investment opportunities 0.17 1.87*** 1.68*** 1.57*** (0.49) (5.23) (3.83) (4.80) Dominance Index (DI) 0.11 -0.04 -0.20* -4.43* (0.62) (-0.19) (-1.66) (-1.82) Cash flow -0.21 -1.58*** -1.41*** -1.15*** (-0.64) (-4.48) (-3.18) (-3.57) Firm size 1.27*** 2.64*** 2.40*** 2.13*** (3.92) (7.35) (5.01) (5.63) Capital intensity 0.17 -0.03 0.02 0.05 (0.49) (-0.24) (0.18) (0.50) Constant -10.50*** -4.34* -4.42*** -3.53*** (-4.82) (-1.81) (-4.38) (-4.62) Observations 118 107 147 118 F 207.74*** 132.86*** 112.14*** 456.12*** Prob > F 0.00 0.00 0.00 0.00 R2 0.90 0.86 0.79 0.95 This table reports results for OLS regressions. They use the Dominance Index as a proxy of market structure. The dependent variable is investment. The results are presented for firm size. The t-statistics are given in parenthesis. ***, **, and * indicate significance at the 1, 5 and 10 percent levels respectively. 65
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    A. Ruiz-Porras, C.López-Mateo | AT ♦ Vol. 2 ♦ No. 1 ♦ 2010 Like in the previous set of regressions, the results show high values of R2. Such values confirm that the explanatory variables can explain investment decisions. Again the F tests confirm that the set of independent variables explains them. So, apparently both sets of regression may provide similar information. The only exception relies on the positive and significant coefficient associated to the market concentration variable for micro firms in the first set of regressions. We support the robustness of our previous results with specification-error Ramsey tests. Such tests allow us to deal with the differences of information. Here we use two versions of the Ramsey test. The first one, the traditional RESET test, uses powers of the estimated independent variable as regressors. The second one uses powers of the RHS variables. The null hypothesis is that the model is adequately specified in both versions of the test. The outcomes of the tests of both sets of regressions suggest that the econometric assessments for small, medium and large firms do not have specification errors. The modeled relationships between market concentration and investment decisions seem adequate in most cases. However, the exception is referred to micro firms. For these firms, the regressions suggest the existence of omitted variable-bias and/or incorrect functional forms. The Ramsey tests suggest that the differences reported between the two sets of regressions should not be considered relevant. In fact, the comparison of the reported outcomes and tests suggest that the regressions that include the DI index might be better than the ones that include the HHI index. We support this statement on the basis that the only significant coefficients associated to the concentration variables appear in the second set of regressions (see Table 5). As we have indicated, the regression of the first set associated to the micro firms has specification errors (see Tables 4 and 6). Here is important to point out that the outcomes suggest that how market concentration affects investment decisions depends on the size of the firms. According to the regressions with the DI index, it seems that concentration significantly reduces investment for medium and large size firms. When firms are micro or small ones, the evidence is not conclusive due to specification errors and non significant variables (see Table 5). Table 6: Model Validation (Specification Tests) Firm size Micro Small Medium Large Models with Herfindhal-Hirschaman Index (HHI) Ramsey test (H0: Model has no specification error) 7.06*** 0.85 2.24* 0.82 Prob > F 0.0002 0.4720 0.0859 0.4875 Ramsey test, rhs (H0: model has no omitted variables) 2.66*** 0.76 0.80 0.81 Prob > F 0.0020 0.7197 0.6788 0.6655 Models with Dominance Index (DI) Ramsey test (H0: model has no omitted variables 7.68*** 0.90 2.35* 0.43 Prob > F 0.0001 0.4465 0.0750 0.7287 Ramsey test, rhs (H0: model has no omitted variables) 2.84*** 0.75 0.74 0.66 Prob > F 0.0011 0.7295 0.7434 0.8123 This table shows results of Ramsey test. It is used to detect specification errors. This table shows two versions of the of the Ramsey test. Ramsey test (rhs) uses powers of the independent variables. Instead Ramsey test uses powers of the fitted values of the dependent variable. ***, **, and * indicate significance at the 1, 5 and 10 percent levels respectively. We conclude by indicating that the evidence supports the view that market concentration reduces investment, at least in medium and large firms. Thus, according to our results, competition may promote 66
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    ACCOUNTING & TAXATION♦ Volume 2♦ Number 1 ♦ 2010 investment. Furthermore the evidence provides elements to support the statistical adequacy of the DI index as an adequate measure of market concentration. Moreover, the results suggest that the regressions that include the DI index might be better than the ones that include the HHI index. DISCUSSION Here we have assessed the relationships between market structure and investment decisions in the Mexican manufacturing firms. The assessments suggest that market concentration may reduce investment, at least in medium and large firms. Thus, competition may promote investment. Furthermore, they confirm that certain firm characteristics may be useful to explain investment decisions. Particularly, firm size seems an important determinant. However, it is interesting to point out that some findings seem counter intuitive. For example, capital seems not to influence investment decisions. Furthermore, cash flows seem to have an inverse relationship with investment. We believe that such findings may be explained on the basis that manufacturing firms are intensive in labor. When firms are labor-intensive, investments may rely on new “costly” workers that reduce cash flows. Methodologically, the assessment procedure seems useful to explain the investment decisions of small, medium and large firms. Furthermore, it supports the hypothesis that investment decisions in micro firms may depend on other determinants, in addition to the market structure ones. Ekanem and Smallbone (2007) include, among these determinants, the intuition, the social networks and the experience of the entrepreneurs. Empirically, we believe that the most interesting findings relate to the usefulness of the different market concentration measures. Our econometric assessment suggests that the Dominance Index (DI) is a better determinant of investment decisions than the Herfindahl-Hirschman Index (HHI). In practice, this finding implies that the degree of competition can affected by differences in the size of the firms in the market. Thus regulators may need to consider these differences when dealing with competition issues. We conclude by indicating that our findings have implications for regulatory and policy purposes. Probably, the most important one is associated to the necessity to promote the Dominance Index as an alternative measure of market competition. Another one relates to the necessity to encourage competition among the Mexican firms in order to increase investment. Finally, a third one relates to the necessity to encourage studies on the determinants of investment in micro and small size firms because our evidence is not conclusive. CONCLUSIONS We have studied how alternative measures of market concentration, as proxy indicator of market structure, may explain investment decisions of Mexican manufacturing firms. Here we have focused on the HHI and the DI measures. We have developed an econometric analysis that uses data for the last census available in Mexico (2003). We have controlled by firm size, cash flow, capital intensity and investment opportunities. Methodologically, the empirical study has relied on two regression sets. The first set includes estimations that use the HHI index as measure of market concentration. The second one includes estimations that use the DI index. We have used OLS techniques for estimation purposes. In addition, we have used Ramsey tests to validate the econometric outcomes. We have used data of the census to build the indicators of the 182 industries that integrate the Mexican manufacturing sector. 67
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    A. Ruiz-Porras, C.López-Mateo | AT ♦ Vol. 2 ♦ No. 1 ♦ 2010 Our findings confirm that market structure may influence investment decisions. Concretely they suggest that concentration may reduce investment. Thus they confirm the findings of Akdoğu and MacKay (2008). Our findings also suggest that the DI index is a better determinant than the HHI one. Furthermore, they suggest that firm size and investment opportunities have a direct relationship with investment. Cash flows, on the other hand, have an inverse one. Interestingly, capital intensity is not related to investment decisions. We believe that our study provides some ideas for further research. For example, extensions of our analysis could be used to analyze investment decisions in firms that provide financial and non-financial services. The “Economic Census 2008”, when available, may provide data useful for comparison purposes. Finally, our results also suggest that further studies on the determinants of investments in micro and small firms may be necessary. REFERENCES Adelegan, O.A. & Ariyo, A. (2008) “Capital Market Imperfections and Corporate Investment Behavior: A Switching Regression Approach Using Panel Data for Nigerian Manufacturing Firms”, Journal of Money, Investment and Banking, vol. 2, March, p. 16-38 Akdoğu, E. & MacKay, P. (2006) “Externalities and Corporate Investment”, Working Paper Series, February, p. 1-39 ______ (2008) “Investment and Competition”, Journal of Financial and Quantitative Analysis, vol. 43(2), June, p. 299-330 Bøhren, Ø., Cooper, I. & Priestley, R. (2007) “Corporate Governance and Real Investment Decisions”, European Finance Association, Working Paper, March, p. 1-29 Bokpin, G.A. & Onumah, J.M. (2009) “An Empirical Analysis of the Determinants of Corporate Investment Decisions: Evidence from Emerging Market Firms”, International Research Journal of Finance and Economics, vol. 33, November, p. 134-141 Czarnitzk, D. & Binz, H.L. (2008) “R&D Investment and Financing Constraints of Small and Medium- Sized Firms”, Discussion Paper No. 08-047, Centre for European Economic Research, p. 1-28 D'Erasmo, P. (2007) “Investment and Firm Dynamics”, Working Paper, University of Texas at Austin, July, p. 1-33 DeMarzo, P.M. & Fishman, M.J. (2007) “Agency and Optimal Investment Dynamics”, The Review of Financial Studies, Oxford Journals, vol. 20, January, p. 151-188 Ekanem, I. & Smallbone, D. (2007) “Learning in Small Manufacturing Firms. The Case of Investment Decision Making Behavior”, International Small Business Journal, vol. 25(2), April, p. 107-129 Escrihuela-Villar, M. (2008) “Innovation and Market Concentration with Asymmetric Firms”, Economics of Innovation and New Technology, vol. 17(3), p. 195-207 García Alba Iduñate, P. (1990) “Un Enfoque para Medir la Concentración Industrial y su Aplicación al Caso de México”, El Trimestre Económico, vol. LVII (226), Abril-Junio, FCE, México, p. 317-341 Lee, M.H. & Hwang, I.J. (2003) “Determinants of Corporate R&D Investment: An Empirical Study Comparing Korea’s IT Industry with Its Non-IT Industry”, ETRI Journal, vol. 25(4), August, p. 258-265 68
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    ACCOUNTING & TAXATION♦ Volume 2♦ Number 1 ♦ 2010 Mishra, V. (2007) “The Determinants of R&D Expenditure of Firms: Evidence from a Cross-Section of Indian firms”, Economic Papers, vol. 26(3), September, Economic Society of Australia, p. 237-248 Ten Kate, A. (2006) “The Dominance Index in Mexican Merger Control: Does it Perform Better than the HHI?”, The Antitrust Bulletin, vol. 51(2), Summer, p. 383-409 Ughetto, E. (2008) “Does internal finance matter for R&D? New evidence from a panel of Italian firms”, Cambridge Journal of Economics, vol. 32(6), April, p. 907-925 BIOGRAPHY Antonio Ruiz-Porras is professor and researcher in the Department of Quantitative Methods at the University of Guadalajara. Address for correspondence: Departamento de Métodos Cuantitativos. Universidad de Guadalajara, CUCEA. Periférico Norte 799. Núcleo Universitario Los Belenes, 45140. Zapopan, Jalisco, México. Telephone: ++ (52) (33) 3770 3300 ext. 5291. Fax: ++ (52) (33) 3770 3300 ext. 5227. Email: [email protected] Celina López-Mateo is student in the Doctoral Program of Economic and Managerial Sciences at the University of Guadalajara. Address for correspondence: Programa Doctoral en Ciencias Económico- Administrativas. Universidad de Guadalajara, CUCEA. Periférico Norte 799. Núcleo Universitario Los Belenes, 45140. Zapopan, Jalisco, México. Email: [email protected] 69