Newsgroups: sci.space.history
From: Henry Spencer <henry@zoo.toronto.edu>
Subject: Re: What if . . . ???
Date: Sat, 3 Jan 1998 19:39:20 GMT

In article <34adafb2.32102950@nntp.ix.netcom.com>, om <om@ix.netcom.com> wrote:
>>   The Moon's gravitational pull cannot and does not affect our moods.
>
>....This is not an absolute, Simon. One of my many professions involves
>dealing with large numbers of women - to be specific. "exotic dancers"
>- and even they admit that their moods and menstrual cycles become
>adversely affected when a full moon is in effect. Liquor sales to
>women go up during full moon phases, and emotional outbursts become
>more frequent and violent.

While I'm not aware of any study done on this particular issue, all
systematic attempts to look for a full-moon effect in areas alleged to be
affected by it -- e.g., hospital emergency admissions -- have come up with
nothing.  The effect isn't there; it's pure superstition.

How do such superstitions get started?  Well, probably two ways.

First, the period of the weekday/weekend cycle is almost an exact fraction
of the period of the lunar cycle.  Liquor sales and consumption are much
higher on weekends.  So every now and then, for several months running,
liquor sales and all that accompany them -- accidents, violence, quarrels,
even many medical problems -- *do* peak at roughly the time of the full
moon, because they peak on weekends and the moon is roughly full then.  So
people notice this.

And second, then the slightly-mismatched periods shift and for a while the
peaks stop coming roughly at full moons... but people *don't* notice that.
People notice the unusual, and fail to notice the commonplace.  Full moons
when all is quiet don't get their attention.

That's how superstitions get started.  It's especially easy for full-moon
superstitions to get started, because you get "hits" for several months in
a row, which seems to confirm observations made during the first one or
two.  By the time the "misses" start, people believe, and they've stopped
paying attention.

There are also some real, if weak, lunar effects in areas where outdoor
activities are important and nighttime illumination affects nighttime
activity levels.

To get an accurate picture of such things, you have to rigorously collect
data on the negative cases as well as the positive ones... and when you've
got complete data, usually it does not take statistical wizardry to see
that there are cyclic patterns but no *consistent* correlation.

The whole reason why statistics evolved as a systematic field of study is
that human beliefs are not a reliable guide to the truth in such matters.
There is no substitute for numbers.
--
If NT is the answer, you didn't                 |     Henry Spencer
understand the question.  -- Peter Blake        | henry@zoo.toronto.edu

Newsgroups: sci.space.history
From: Henry Spencer <henry@zoo.toronto.edu>
Subject: Re: What if . . . ???
Date: Mon, 5 Jan 1998 16:01:17 GMT

In article <34B07E41.3303@ix.netcom.com>,
Ken Hayashida, MD <khayash@ix.netcom.com> wrote:
>> >While I'm not aware of any study done on this particular issue, all
>> >systematic attempts to look for a full-moon effect in areas alleged to be
>> >affected by it -- e.g., hospital emergency admissions -- have come up with
>> >nothing.  The effect isn't there; it's pure superstition.
>
>Hmmm.... somehow I remain unconvinced that Henry Spencer knows the
>number of hospital ER visits on nights of full and/or new moons and
>can compare them.

Personally, I have no idea what they are.  However, it is not necessary
for me to rely on personal experience; the data has actually been gathered
and looked at statistically, in proper studies, and the results have been
completely negative.

For emphasis, I repeat a previous comment of mine:  "personal experience"
is almost totally valueless in this area, because of the well-understood
process of the formation of superstitions.  The only way to get reliable
results is to carefully record negative as well as positive instances,
and "personal experience" doesn't do that.
--
If NT is the answer, you didn't                 |     Henry Spencer
understand the question.  -- Peter Blake        | henry@zoo.toronto.edu