What Nick Stokes Wouldn’t Show You

Climate Audit

In MM05, we quantified the hockeystick-ness of simulated PC1s as the difference between the 1902-1980 mean (the “short centering” period of Mannian principal components) and the overall mean (1400-1980), divided by the standard deviation – a measure that we termed its “Hockey Stick Index (HSI)”.  In MM05 Figure 2, we showed histograms of the HSI distributions of Mannian and centered PC1s from 10,000 simulated networks.

Nick Stokes contested this measurement as merely a “M&M creation”.  While we would be more than happy to be credited for the concept of dividing the difference of means by a standard deviation, such techniques have been used in statistics since the earliest days, as, for example, the calculation of the t-statistic for the difference in means between the blade (1902-1980) and the shaft (1400-1901), which has a similar formal structure, but calculates the standard error in the denominator as a weighted average of the…

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