Regression to the mean and climate change stupidity


regressionThe figure above is from one of the most important and most influential scientific papers ever published: Regression Towards Mediocrity in Hereditary Stature in volume 15 of “The Journal of the Anthropological Institute of Great Britain and Ireland” (in fact JSTOR claims it is copyright to them from 1886, but I am betting that the copyright has lapsed).

In this paper the eminent Victorian scientist Francis Galton showed that, actually, the children of taller people tended to be smaller than their parents and vice versa – an example of the phenomenon we would now call “regression towards the mean“.

Such regressions do not replace longer-term trends (you can see from the figure above that Galton estimated the average height of adult males to be just over 5 foot 8 inches – about my height – and today the figure is closer to 5 foot 10 inches), instead they are a reflection of the random noise in the system.

But although this has been understood by scientists since 1886, it seems it has yet to penetrate the Mail on Sunday – who claimed that because the retreat of arctic sea ice in 2013 did not match 2012’s all-time record the science of climate change was dead in the water.

In fact the trend, regression towards the mean notwithstanding, is pretty clear – as this ought to make clear to anyone able to read any sort of plot…

Sea ice extent