The document discusses the responsibilities of a data scientist working with big data. A data scientist must ensure smooth loading of large amounts of data from various sources, fetch the data quickly without errors, and create a big data dictionary that can be used to present information to end users according to business rules. The data scientist should understand the entire data flow, including business rules and processes, and present information to users in an accessible way. They require expertise in technologies like Hive, Spark, MapReduce, Pig and Cassandra to work with large datasets.