To: All Msg #41, Oct2692 08:59AM Subject: Re: +quot;Mars Effect+quot;: JWN replies Ertel
From: Jan Willem Nienhuys
To: All Msg #41, Oct2692 08:59AM
Subject: Re: "Mars Effect": JWN replies Ertel's 23/10 post (pt 2a)
Organization: Eindhoven University of Technology, The Netherlands
From: wsadjw@rw7.urc.tue.nl (Jan Willem Nienhuys)
MessageID: 6050@tuegate.tue.nl
ReplyTo: wsadjw@urc.tue.nl
Newsgroups: sci.skeptic
In article <6049@tuegate.tue.nl> wsadjw@urc.tue.nl writes:
>#
># 2.5 Inferential statistics.
>#
>#Dr. Nienhuys came up with z = 1.23 as deviation of observed Mars
>#born athletes (N = 271/1,076) from chance expectation which he
>#estimated as N = 247/1,076 (G% = 22.93%). "Not impressive", he
>#says. Error probability would be p = .11, so his statement could
>#be rephrased by "not significant" ,i.e., not reaching
>#p = .05, the conventional significance level.
I calculated from Gauquelin 1972 (or rather from a table
quoted there) on the basis of the mentioned 24,961 "ordinary
people" that 22.9% is correct. I interpolated the expected values
given for the 12sector distribution (with sectors 1,2,3 and 10,11,12
making up rising and culminating standard sectors) to values for sectors
36 and 9, and arrived at the 22.9%. Originally I had applied the
ratio 17.2/16.67 to 8/36, giving about the same. It doesn't matter
whether one does it with the theoretical values or the actual observed
values in that table.
>As Professor Ertel will recall, I estimated the standard deviation
>at about 14 absolute, no matter what the exact value was for G%.
>
>However, the z = 1.23 was computed not from the 22.93 estimate,
>but from another one, namely the middle value 23.6 of Ertel's shift
>simulations. (Which I told Ertel, on his request). I clearly stated
>(I think) that I don't know the "true" expected value.
I guess the middle value (from a uniform distribution coming out of
Ertel's method) should be discarded. If we believe 22.9%, then
this gives z = 1.78. Interesting, unless you insist on twosided
tests.
>#Zelen's expectancy of 21.84%. Now, if we use as control 21.84%
>#obtained by unsuspected skeptics and essentially confirmed by my
>#"replication", the indicator z for CFEPP's Mars G% with athletes
>#(N = 271) goes up: z = 2.658 , p = 0.0039. That is, even if we
>#follow Dr. Nienhuys' statistical approach and do it correctly the
>#result strongly supports the Gauquelin hypothesis.
Observe the interesting discrepancy between 21.8 and 22.9, both
coming out of a tabulation of results of about 20,000 people.
Statistical theory says that the uncertainty in the percentage
should be around 0.3 percent. And now we have a difference of
3 times that. "Hurray, again something significant"?
(Twosided at the 0.05 level! Chisquared = 4.1, 1 df, roughly)
Certainly not. No prior hypothesis. No test to check
especially that hypothesis. Just an indication that this type of
data *might* have more scatter to it than those nice binomially
distributed variables from probability theory.
JWN
BTW, is anybody really interested in this, except Ertel and me?
I hate to think that this is degenerating into some kind of
SS (sianosheaffer) dispute.
EMail Fredric L. Rice / The Skeptic Tank
