It has been said that the first three laws of statistics are:
Statistics alone can be misleading.
The human mind did not evolve to understand concepts by reading words and numbers on a page. It is much more visual. Pictures can help give us an intuitive understanding that words and numbers cannot.
Here's an example. We're trying to determine if there is Correlation between the x and y values for either of the two Samples of data pictured below.
We calculate a Statistic for each Sample, r, the Correlation Coefficient. The value of r for these two plots are almost identical – and in both cases, it indicates a very strong Linear Correlation.
That makes sense for the one on the left. However, the one on the right is not linear at all. That data would more likely to be approximated by a polynomial curve.
Andrew A. (Andy) Jawlik is the author of the book, Statistics from A to Z -- Confusing Concepts Clarified, published by Wiley.