Hands-On Data Analysis with Pandas

Quantifying relationships between variables

In the previous sections, we were dealing with univariate statistics and were only able to say something about the variable we were looking at. With multivariate statistics, we can look to quantify relationships between variables. This allows us to look into things such as correlations (how one variable changes with respect to another) and attempt to make predictions for future behavior.

The covariance is a statistic for quantifying the relationship between variables by showing their joint variance:

E[X] is new notation for us. It is read as the expected value of X or the expectation of X, and it ...