2003 paper by Stephen McIntyre and Ross McKitrick published in Energy and Environment which alleged that correction of errors in MBH99 would show a strong medieval warm period, and said this paper raised pertinent questions. In an October 2004 Technology Review article, Muller discussed blog postings by McIntyre and McKitrick alleging that Mann, Bradley and Hughes did not do proper principal component analysis (PCA). In the article, Richard Muller stated: McIntyre and McKitrick obtained part of the program that Mann used, and they found serious problems. Not only does the program not do conventional PCA, but it handles data normalization in a way that can only be described as mistaken. Now comes the real shocker. This improper normalization procedure tends to emphasize any data that do have the hockey stick shape, and to suppress all data that do not. To demonstrate this effect, McIntyre and McKitrick created some meaningless test data that had, on average, no trends. This method of generating random data is called "Monte Carlo" analysis, after the famous casino, and it is widely used in statistical analysis to test procedures. When McIntyre and McKitrick fed these random data into the Mann procedure, out popped a hockey stick shape! That discovery hit me like a bombshell, and I suspect it is having the same effect on many others. Suddenly the hockey stick, the poster-child of the global warming community, turns out to be an artifact of poor mathematics. How could it happen? He went on to state "If you are concerned about global warming (as I am) and think that human-created carbon dioxide may contribute (as I do), then you still should agree that we are much better off having broken the hockey stick. Misinformation can do real harm, because it distorts predictions." In an article on the RealClimate blog on various myths about the graph, Mann mentioned Muller's article as parroting the claims of McIntyre and McKitrick. Muller's opinion piece in the reputable MIT journal helped to spread the idea that the hockey stick shape was a statistical artifact, but several peer reviewed studies showed that the PCA methodology had little effect on the shape of the graph. By 2006 there was general acceptance of the conclusion of the graph that recent warming was unprecedented in 1,000 years. Berkeley Earth In October 2011, Muller wrote in an op-ed in The Wall Street Journal, concerning his work with