As mentioned in Chapter 1, exploratory data analysis or “EDA” is a critical
first step in analyzing the data from an experiment. Here are the main reasons we
use EDA:
• detection of mistakes
• checking of assumptions
• preliminary selection of appropriate models
• determining relationships among the explanatory variables, and
• assessing the direction and rough size of relationships between explanatory
and outcome variables.
Loosely speaking, any method of looking at data that does not include formal
statistical modeling and inference falls under the term exploratory data analysis.