How should statisticians teach Pearson’s legacy?

Introduction

Karl Pearson (1857-1936) was a brilliant mathematician whose contribution to modern statistics cannot be overstated. To him we owe chi-square, the Pearson product-moment correlation coefficient, contingency coefficient, coefficient of skewness, kurtosis, regression to the mean, and numerous other important methods. A student of statistics today cannot avoid citing Pearson, his name being ubiquitous within the turn-of-century statistical revolution of Pearson, Spearman and Fisher.

As David Sheskin (2011: 69) comments,

Along with Sir Ronald Fisher, Pearson is probably viewed as having made the greatest contributions to what today is considered the basis of modern statistics.

But this titan of statistics was also a racist, whose racism permeated his chosen scientific discipline: eugenics. This was not an accident, as a recent inquiry at the institution that employed him, University College London (UCL), has revealed. Financially supported by another eugenicist and man of means, Sir Francis Galton, Pearson ran his own laboratory at UCL. Galton (1822-1911) is credited with the introduction of regression and correlation, upon which Pearson built.

Why is statistics difficult?

Imagine you are somewhere on a road that you have never been on before. Picture it. It’s peaceful and calm. A car comes down the road. As it gets to a corner, the driver appears to lose control, and the car crashes into a wall. Fortunately the driver is OK, but they can’t recall what happened.

Let’s think about what you experienced. The car crash might involve a number of variables an investigator would be interested in.

• How fast was the car going? Where were the brakes applied?
• Look on the road. Get out a tape measure. How long was the skid before the car finally stopped?
• How big and heavy was the car? How loud was the bang when the car crashed?

These are all physical variables. We are used to thinking about the world in terms of these kinds of variables: velocity, position, length, volume and mass. They are tangible: we can see and touch them, and we have physical equipment that helps us measure them.