Around 20% of GRE questions involve "data analysis." These questions typically involve looking at data/graphs/tables in order to find certain values, like the median or percent change. Other questions ask about important statistical concepts, like the normal distribution.
All the posts in this series can be found here:
- What is Data? Variables and frequencies
- Statistical Concepts
- Reading Graphs: An Introduction
- Normal distributions
Content for other parts of the math GRE can be found here: