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On Mon, 18 Aug 2003, Axel Harvey wrote:
> I presume you have seen the bet in Gerard 't Hooft's web pages. It
> seems to be aimed squarely at the GCP. He even links your site.
>
> http://www.phys.uu.nl/~thooft/parabet.html
> http://www.phys.uu.nl/~thooft/paraplue.html
>
> (The link to the GCP site is reached from the latter URL. Go to the
> bottom of that page and click on "scientifically detected".)
>
> Maybe you have mentioned this already in your website or emails -
> sorry if I've missed it. What do you think?
I appreciate Gerard 't Hooft's interest and his willingness
to take the time to think about the GCP database and results.
It is a large corpus and thus it is perhaps understandable that
he is not (apparently) aware of some aspects of the database
that are relevant, and has incorrect impressions about the
types of events we assess.
I had not seen his web page yet, though I have been in contact
with 't Hooft once directly and other times indirectly by way
of my colleague Dick Bierman. Thus I am aware of his basic idea.
It is not a bad proposal in some respects, but it is ungainly and
demonstrably unnecessary for a substantial proportion of the GCP
database, even if one believes there are grounds for his concern.
In addition, because he is looking for 5 sigma, it would, according
to our experience (and statistical power estimates), require on
the order of 100 events (about 2.5 years at our average rate) to
have even .5 beta of reaching such a level. His plan also requires
that everybody be blind to the data and that "An experiment must
be analyzed in one single procedure, immediately after disclosure
of its results." Together, if I understand him correctly, these
conditions would require that we run the experiment blind for
two or three years.
I have suggested to 't Hooft an alternative procedure that is
also immune to the problem he is concerned about, namely:
"In this particular [GCP] case, the point is that whatever
'emotionally distressing events' are, is defined while the
experiment takes place."
That statement or description is not true for a substantial proportion
of the GCP events that constitute the experiment. I suggest
that for cases that are specified a priori, that is, before
the event takes place, none of the concerns or preferred
"explanations" in 't Hooft's description are valid. Thus, I
propose that the results for the a priori cases be examined
and compared with those that are necessarily specified after
the fact. This is a simple and instructive test of the
viability of 't Hooft's criticism.
About 45% of the formal predictions can be and are established
before the event. For example, we have each year made predictions
about the New Year transition period. Obviously, these can be
made ahead of time. Similarly, for web- or media-organized global
peace marches, or major religious gatherings or meditation events,
we know the publicized,
planned time and can make an a priori prediction. There actually
are a considerable number of potentially interesting, often
unique events for which such a priori specification is possible:
The moment of the Dow Jones Industrial Average first breaking
the 10,000 barrier; the major solar eclipse over Europe and the Middle
East in August 1999;
openings of the Olympic games; the Kumbh Mela in India; Earth
Day celebrations; and so on. We have as of August 2003 a total
of 147 formal predictions and tests of the general hypothesis that there
will be departures from expected random behavior in the GCP data that
are correlated with major global events. Of the 147 events or cases,
67 are defined by a priori predictions, and 80
are post facto because
they address accidents, explosions, disasters, events of war,
etc., which cannot be subject to a priori specification.
So, 't Hooft's description, above, is not and cannot be
relevant to a substantial number of cases in the GCP database.
The question is whether these cases show less evidence for
the correlations we see overall in the database. The answer
is no -- indeed they present a somewhat more persuasive bottom line.
The a priori cases have a smaller mean probability
(0.354 vs 0.410 for the post facto subset), and despite the
smaller database size, they actually have a more extreme composite
p-value (1x10e-6 vs 9x10e-4 for the post facto subset).
Going beyond this simple demonstration, Dick Bierman and I
are discussing and preparing to test a procedure that meets,
even for the post hoc cases, the standards 't Hooft proposes,
while also allowing the project to proceed with little
interference. Although I don't intend to engage in the
Randi-style "bet" that 't Hooft uses to express his
depth of conviction, I will keep him informed.
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