There was a small error in the calculation of regression coefficients in our paper. Our conclusions were not affected by this problem
As I noted in my post, correcting the error halves the size of the economic signal in the warming trend, reducing it from 0.16 (out of 0.27) to 0.09. McKitrick’s correction states:
Outside the dry/cold regions the measured temperature change is significantly (previous: primarily ) influenced by economic and social variables.
That’s quite a difference, so how can he say that their conclusions were not affected? Well, all the conclusion says is that there were socioeconomic effects, without mentioning their size. The size of the effects, which change substantially, are only mentioned in the body. And the “bombshell” nature of the paper touted by Michaels et al in their TCS article depends on socioeconomic effects being the primary cause of the warming trend, something that McKitrick has now retracted.
McKitrick has also failed to correct or even acknowledge another serious problem in his paper—he has not corrected his standard errors for clustering. This is required because his socioeconomic variables are all the same for the stations in the same country. This means he will find some variables to be statistically significant when they are not really so.
Nor has McKitrick explained why he decided to take the cosine of the absolute latitude in the first place. Calculating it correctly makes no difference to the model, while calculating in incorrectly makes the model fit worse. There does not seem to be any theoretical or empirical justification for this change to his model. As John Quiggin observes:
a trawl back through the files makes it pretty clear that this error was not exactly an innocent mistake. It seems pretty clear that McKitrick tried some regressions with (absolute) latitude as the explanatory variable, didn’t like the results he got and switched to the cosine (note that, if you were starting here, you wouldn’t need to take the absolute value, since cosine is a symmetric function). Because of the degrees-radians mistake, this variable came out insignificant, as desired, and McKitrick didn’t do the checks that would have revealed the error. Asymmetric error-checking is a standard problem with cherry picking, as illustrated by the work of John Lott.