reading time: 10 min. Pearson’s correlation (short: correlation) is one of statistics’ all time classics. With an age of about a century, it is some kind of grand dad of analytic tools – but an oldie who is still very busy! Formula, interpretation and application of correlation is well known. In some non-technical lay terms, correlation captures the (linear) degree of co-variation of two linear variables. For example: if tall people have large feet (and small people small feet), on average, we say that height and foot size are …