Actividad3 david a. condori tantani

Session 1
Module Introduction and Getting Started with
Stata
1
Lic. David A. Condori Tantani

2
Introduction
 Welcome
 Housekeeping
 Introductions
 Name, job, district, team
2

Module Overview
3
Module objectives are to provide you with
• Skills in data analysis
• Keeping in mind the analysis objectives
• While learning the use of a specialised
statistical software package Stata
There will be a strong emphasis on conducting
meaningful analyses and on the interpretation
of the results.

4
Module content
 Data management
 Data entry principles and practices
 using Epi Info
 designing data capture screens,
 labelling and entering data, etc.
 Simple statistical analysis
 in Epi Info
 and using the statistics package, Instat.
 Report writing.
4

5
Duration and timetable
5
Morning Afternoon
Day 1
Getting started with
Stata
Continued
Day 2 Tables Project work part 1
Day 3 Graphs Project work part 2
Day 4
Reviewing inference:
estimation and
confidence intervals
Reviewing inference:
Hypothesis testing
Day 5
Tests of association in 2-
way tables
Sampling weights
Day 6
Project work part 3:
writing the report
Putting it all in context

6
Module Learning Objectives
At the end of the module, participants will :
 appreciate the power of Stata as a statistical package
 be able to undertake elementary data management
and statistical analyses in Stata
 have updated their practical knowledge of the key
statistical inference concepts of estimation and
hypothesis testing
 be able to produce graphs and tables using Stata,
 have sufficient knowledge of Stata to be able to work
independently to produce other analyses
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7
Prerequisites
Completion of Modules 1 and 2
At least a theoretical knowledge of statistical inference
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8
Resources
 Stata software - version 10
 This should be installed already
 It may need updating and a Stata “package” adding – see later slides
 Guide to survey data analysis using Stata
 Part 1 (Chapters 1 to 10) is used here
 Part 2 (Chapters 11 to 20) is supplied for reference
 Inference guide
 Used particularly in Sessions 7 and 8
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Concepts more than software
 The emphasis is on the concepts of data analysis and statistical inference
 Using Stata
 Rather than just on Stata itself
 Here we largely use the menus and dialogues
 Though ways of using and reading commands are introduced
 Software is now easy to master
 It is the statistical concepts that benefit from a course

Learning objectives –
sessions 1 and 2 These two sessions are about Stata
 Participants will be able to:
 Load and save data
 Explore data
 Using describe, codebook, summarize, etc
 Calculate new variables
 Using generate, recode, etc
 Add labels to variables and to levels of a factor
 Create subsets of data using drop and keep
10

Session Contents
11
In this session we look in particular at:
• Windows and menus in Stata
• Opening Stata data files
• Stata dialogues
• Typing and editing commands
• Using Stata as a calculator
• Exiting Stata

The four Stata windows
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Review
Stata
Results
Variables
and
window for
typing
Stata
commands

The Stata menus and toolbar
 The three most important menus
 Data (for organising and managing the data),
 Graphics (for visual exploration & presentation),
 Statistics (for analysis).
13
Data, Graphics, Statistics

Check Stata is up-to-date
 Use Help => Official updates
14
If updating is
needed, either:
Do it
automatically if
you are
connected to the
internet
Or use the files
on the CD/DVD
that are under
Stata resources

The Data and Graphics Menus
15

Your turn
 Click on several menus and explain their
usage to your neighbour
 You can deduce the menu from the logic of the
task
 e.g. to draw a graph you go to the graphics menu!
 Which menu would you probably need to use to:
 save data?
 sort a data set?
 produce a bar chart?
 tabulate the data?
 Check by finding the dialogue in Stata
16

Stata guide Section 1.2
 You use Stata as a calculator
 Go through this section together
 Check the buttons at the bottom of the dialogue
 They are the same on all dialogues
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Using Stata as a calculator
To perform calculations, use
Data ⇒ Other utilities ⇒ Hand calculator
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Type 2+3 into the
Expression slot
Press the
Submit button
See answer in Results Window, and appearance of
corresponding command in both the Results and
Review windows.

Results from the dialogue
You can get back
to any dialogue
box by typing db in
front of the
command name.
e.g. db display
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Creating an expression
20
Click create and
then complete
the resulting
expression
builder dialogue
box.
Or type:
display ln(10)

Stata guide Section 1.3
 From this point you use a dataset that is supplied
 Check that you have a working directory
 And that it has the files for this module
 Copy them in, if not
 They are on the CD/DVD under Stata resources
 You could install the Stata package as well if you wish.
 Then use Files => Change working directory
 To set this directory for the future
21

Opening a Stata data file
 Use the menu sequence
 File, Open…
select (highlight) the file named
 K_combined_short.dta
and click on Open
 This will load the data from the Kenya socio-
economic survey into Stata
 Look at the Variables Window. What do
you observe?
22

Options within the Data menu
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An example of a dialogue
box24
Dialogue results from
using the menu
sequence
Data,
⇒ Describe data,
⇒ Describe data
contents (codebook)

In the codebook dialogue
box…
 The Submit button
 instructs Stata to execute the command, leaving the
dialogue box visible.
 The OK button does the same,
 but closes the dialogue box.
 Cancel closes the dialogue box
 without submitting the command to Stata.
 The R button resets the dialogue box
 to its empty form.
 ‘?’ gives help on the command
 associated with the dialogue box.
 The word “codebook” at the top of the dialogue
 shows “codebook” is the command that will be
generated
25

Another dialogue box
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Dialogue results from
using the menu
sequence
Data,
Describe data,
Summary
statistics

Results from codebook and summarize
27

Your turn
In Chapter 1 of the Stata guide, go through
 Section 1.3
 Section 1.4
 Section 1.5
Ask a resource person if you are unclear about
any parts of the above sections.
28

Review
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What do each of these buttons do?
Menus (and corresponding commands) used so far:
•display
•describe
•codebook
•list
•generate
•replace
•by/if//in
What does each one do?

Your turn again
 Section 1.6
 Section 1.7
 Section 1.8
Ask a resource person if you are unclear about
any parts of the above sections.
30

Review again
 Explain to a neighbour why:
 (3<4) gives the value 1 in Stata
 (3>4) gives the value 0
 They then explain to you why the expression:
 1 + (age>24) + (age>60)
 Recodes a column into the values 1, 2 or 3
 (Hint – see Section 1.6 Fig 1.19 and 1.20 if you need help)
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Typing and editing commands
 Professional use of Stata for data analysis
 benefits by some use of Stata commands
 These are typed into the Command Window
 To execute a command just press <Enter>.
 To edit a previous command:
 Click on it in the review window,
 or use the Page-Up key – perhaps repeatedly.
 In the Results Window
 A “dot” appears in front of executed commands
 whether generated by a dialogue, or by typing the command.
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Command for listing data
In the command window, typing
list region district household cluster
will show the contents of each of the variables
region, district, household and cluster.
(Note: Stata is case sensitive)
Pressing the GO button (see Stata menu bar) or the
space bar allows you to scroll down the page
To stop the display, press the red break icon button
or press the letter q on your keyboard.
To exit Stata, use:
File ⇒ Exit
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Your turn yet again
 Sections 2.1 and 2.2
 (You can go further if you have time)
If you have your own data
And it is not already in a Stata file, then:
 In Chapter 3 of the Stata guide, go through
 Sections 3.2.1, 3.2.2, 3.2.3
 And discuss importing with the resource persons
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… and finally…
 Consider a data set from your own district or
ministry that is available as an Excel file.
 Follow procedures similar to those in Section
3.2.3 of the Stata Guide, to load your Excel data
set into Stata.
 Save your data as a Stata file, giving it an
appropriate name and noting the directory on
your computer where it has been saved.
Note: You will return to this data set in sessions
that follow.
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Actividad3 david a. condori tantani

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