Washington Post warmist Juliet Eilperin: "Mann and his team used a statistical tool called “principal component analysis” to tease out which factors are most responsible for a given change over time..."

Book review: Michael Mann’s ‘The Hockey Stick and the Climate Wars’ - The Washington Post

Mann and his team used a statistical tool called “principal component analysis” to tease out which factors are most responsible for a given change over time and to compare data from all over the globe.

Two Canadians, mining consultant Stephen McIntyre and economist Ross McKitrick, challenged the hockey stick on a variety of fronts. First they went after the proxy data; later they employed the same statistical tool that Mann and his colleagues did, but in what Mann considers an inconsistent way. The result was a smoothing out of the pattern embodied in the hockey stick. “If there is a lesson” in these sorts of fights, Mann writes, “it is that scientific findings that rest on such technical complexities are prone to abuse by those with a potential ax to grind.”