Technology Review wrote:Canadian scientists Stephen McIntyre and Ross McKitrick have uncovered a fundamental mathematical flaw in the computer program that was used to produce the hockey stick. In his original publications of the stick, Mann purported to use a standard method known as principal component analysis, or PCA, to find the dominant features in a set of more than 70 different climate records.
But it wasn’t so. 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? What is going on? Let me digress into a short technical discussion of how this incredible error took place.
And a graph from the McKitrick's website:
One of those is climate data, the other is random. Which is which? Can't tell, can you?
"preemptive killing of cops might not be such a bad idea from a personal saftey[sic] standpoint..." --Keevan Colton
"There's a word for bias you can't see: Yours." -- William Saletan
That graph is real hard to make out. So what does this mean? That global warming has been unproven?
It's easier to see on a light colored screen. It doesn't mean the global warming has been disproven, but it does mean that one of the evidentiary legs supporting it has been shown to be nonexistant.
"preemptive killing of cops might not be such a bad idea from a personal saftey[sic] standpoint..." --Keevan Colton
"There's a word for bias you can't see: Yours." -- William Saletan
Well Jesus H. Christ, how did people miss this? Didn't other scientists try to duplicate the hockey stick plot independently?
BoTM / JL / MM / HAB / VRWC / Horseman
I'm studying for the CPA exam. Have a nice summer, and if you're down just sit back and realize that Joe is off somewhere, doing much worse than you are.
*sigh*
Let me guess, tomorrow you are posting a statement by creationist who claim to have shown that radio dating does not work. Other have already taken apart this work
Frankly the authors have a history of manipulating data to get the results they want as well as just being stupid,
eg. confusing radian and angles or stating that there is no such think as an avarage temperature, are not trustworthy.
