Posted on 10/15/2004 2:39:25 AM PDT by Goat Locker Freeper
Progress in science is sometimes made by great discoveries. But science also advances when we learn that something we believed to be true isn’t. <>
In the scientific and political debate over global warming, the latest wrong piece may be the “hockey stick,” .... This plot purports to show that we are now experiencing the warmest climate in a millennium, and that the earth, after remaining cool for centuries during the medieval era, suddenly began to heat up about 100 years ago....
-SNIP-
But now a shock: independent Canadian scientists... 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!
-SNIP-
Suddenly the hockey stick, the poster-child of the global warming community, turns out to be an artifact of poor mathematics.
(Excerpt) Read more at technologyreview.com ...
Yeah, I know. I use that argument to see who has actually read the papers in question. It is amazing how many people use that graph without really thinking about what it really means.
So, what did you think of McKitrick's paper "A test of corrections for extraneous signals in gridded surface temperature data"?
So why does the corrected one show such warm temperatures during the little ice age. Did it not take place?
Some of the other criticisms I've seen (Lambert's blog, mostly) are baseless. For example, Lambert went far into lala land when speculating about the choice to use absolute latitude. From looking at McKitrick's archives it is clear that the use of absolute latitude is a vestige of McKitrick's GDP-only earliest version of the paper.
Some other criticisms may have some substance. For example, I'm not sure what to make of the criticism that it's inappropriate to treat surface record data locations as independent in such an analysis, given their economic commonalities.
I holler into the rainbarrel for months at a time while doubting that anyone hears. Thank you!
For lurkers, 'Flight' is a collection of essays on the topic from a conference of the same name - many authors agreeing with 'Higher Superstition'.
Lysenkoism.
Your language seems to suggest that McKitrick might have been as recalcitrant as Mann in owning up to error, if only he had the chance. Shame on ya. Climate Research lists an Erratum from McKitrick and Michaels as #C 525 amongst its "Forthcoming publications". McKitrick posted draft erratum for public comment soon after the degrees-instead-of-radians error was identified.
You are absolutely correct that McKitrick and Michaels could have used "cosine of latitude" instead of "cosine of absolute latitude". One of McKitrick's earlier versions of the paper used absolute latitude without the cosine in examining the relationship between GDP and surface temperature record. The use of cosine was added later in the paper's development. The use of absolute latitude appears to be a vestige of that earlier work.
Vacuumed like the Rose Law Firm files
The vacuuming of Mann's ftp site is a story which warrants the widest publicity. When McIntyre and McKitrick's Energy and Environment article was published, Mann's quick comments were made to the Quark Soup blogger, who promptly published Mann's emails. Mann claimed that McIntyre had requested that the various Mann et al. 1998 time series be compiled into an Excel file for him, and that it was in the course of fulfilling this custom request that the "pcproxy.txt" file got ballocksed-up. Mann also noted that the correct data had long been available via ftp, and provided the ftp URL.
It just so happens, however, that the ftp directory included the same pcproxy.txt file, with a date stamp long before McIntyre contacted Mann. Also in the directory was a pcproxy.mat file -- an output of Matlab analysis software showing the same ballocksing as in the pcproxy.txt file. The Matlab file also had the same earlier datestamp. Within a week or so after Mann made his charges as described above, both the pcproxy.txt and the pcproxy.mat files were removed from the public ftp directory.
The existance of these two files seems to be quite in conflict with the specific claims made by Mann, and undermines the rather unflattering picture Mann paints of McIntyre and McKitrick. McIntyre published the email exchanges between him and Mann and Mann's designee. None of the emails suggest that McIntyre requested Excel file. And I note there's not a whit of public mention of the particular ftp directory before McIntyre and McKitrick's paper was published. I did a google search of web and usenet the day that Mann announced the ftp directory, and nary a mention anywhere was found. I posted my finding that same day in the quite contentious sci.environment group, and nobody contradicted my search results, although two folks assured everyone that they had indeed seen that exact University of Virginia directory at some point in the past. I found their assurances quite unconvincing, given that I too recalled seeing similar ftp directory, such as the one at the University of Massachusetts ftp site documented in one of the original Mann et al. papers. But the often-cited U Mass site did not, apparently ever, include the pcproxy.txt or pcproxy.mat files.
The Rose Law Firm was where Hillary Clinton was a partner. The shredding of records there, records related to Hillary's involvement in such ventures as Whitewater and Castle Grande, has been the subject of much discussion here on FreeRepublic. A search of AlamoGirl's annotated archives would probably be the best way to see a broad range of various article excerpts.
Legates
I had seen Legates' original and Jones' email reply when they were first distributed, but had not realized that Legates made any subsequent changes until you mentioned it here. Thanks. I've since taken the opportunity to compare the modified article with the original, and I'm not concerned in the least. It would have been nice for Legates or NCPA to have included a revision date, but the changes were so minor that I can understand the failure to do so. The biggest changes involved decoupling of "Mann and Jones" in several places, with the specific other Mann co-authors mentioned where appropriate. This did indeed improve the article, and I can understand why Jones didn't want to be tarred with every criticism.
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