Before I do any form of statistical analysis on my data, I always like to get a good look at it. Getting familiar with the data before conducting inferential tests is a good way to understand the data.
Data exploration can take on many forms; most common is perhaps to produce means (or medians) of each group you are investigating and plot them.
This is, of course, fine. However, of late I have become interested in looking at the distributions of my results rather than just an estimate of their central tendency. Looking at just the mean—a point estimate—”throws” a lot of information away. Did all participants in each group perform equally? Were there any participants who performed substantially differently from the group (so-called “outliers”)? Continue reading