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4
Exploratory Analysis
and Introduction to
Inferential Statistics
4.1 EXPLORATORY DATA ANALYSIS (EDA)
Classical parametric statistical inference depends on outlier-free and nearly Gaussian data. Before
applying these inferential methods, it is a good idea to explore the data and see if they conform to
the assumptions (MathSoft, 1999, pp. 3-6–3-8 and 3-14–3-15). One way of accomplishing this is by
visual inspection of several plots. Because it is a rst look at the data, we can refer to this process as
exploratory, thus the term exploratory data analysis (EDA); in other words, use graphs to check the
assumptions before proceeding to formal a ...