From: David C Campbell <amblema@bama.ua.edu>

Date: Tue Sep 06 2005 - 18:26:16 EDT

Date: Tue Sep 06 2005 - 18:26:16 EDT

One major problem with the article is the assumption that all

scientific papers use the statistical methods discussed in the paper.

Many are more descriptive. For example, my papers on the fossil

mollusks of the Carolinas list the species found and provide

descriptions of some of them. Although there may be errors in my

identifications, this does not fall under the issues raised by that

article.

Others papers use different statistical methods (with their own

weaknesses). Although 5% is a classical cutoff, the number of papers

that actually have a 5% error (as opposed to something rather less than

5%) is relatively small.

Although it is true that the statistics are often a weak point for

scientific papers, this does not necessarily totally invalidate the

papers that use them. Furthermore, the papers that use a 5% (or other,

usually smaller) cutoff in the way envisioned in the summary will give

the percent probability, so the reader can judge.

Ironically, a basic claim of the article itself involves bad

statistics. Use of the 95% confidence level does not mean that 1 in 20

papers that use it are wrong, on average. It means that each result

that has a 95% support level individually has a 1 in 20 chance of being

wrong. The probability that x independent items, each with 95%

probability of being correct, are all correct, is (19/20)^x. This is

less than 50% when x=14. However, it never reaches zero. Thus, you

cannot be sure that any of them are incorrect, but there is a greater

than 50% chance that at least one out of 14 samples is incorrect.

Furthermore, additional studies affect the statistics. The odds that

both of two results with 95% confidence are wrong is only 0.28%.

Assuming that all of the studies that point to global warming as a

serious problem are wrong, for example, is unreasonable, even though

there are some people who make unsupported claims about the magnitude

of imminent change.

A serious problem in the way the article is interpreted by some

(refering to the responses posted on the website with the article) is

that it serves as an excuse to ignore scientific papers that you don't

like. In fact, it is the papers that support what you think that

require the greatest scrutiny, because the natural tendency is to

readily accept what sounds good.

Finally, I would note that the low funding for most science makes the

accusation of making up results for financial gain a bit dubious. In

particular, denying global warming has obvious financial benefits,

whereas accepting it as a problem that needs serious attention has

financial costs. That does not prove which is right, but it does point

to a definite risk of bias or pressure.

----------------------------------------

Dr. David Campbell

425 Scientific Collections

University of Alabama, Box 870345

Tuscaloosa AL 35487

"James gave the huffle of a snail in

danger But no one heard him at all" A.

A. Milne

Received on Tue Sep 6 18:27:46 2005

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