Science versus Supposition
In 1989 on the Today Show Bryant Gumbel, a very intelligent
man, interviewed Dr. Charles Hennekens about a groundbreaking study that showed
participants in a Harvard study reduced their incidents of heart attacks by 47%
by taking one aspirin every other day.
Gumbel then asked – Could you reduce the risk of a heart attack by 94%
by taking one aspirin every day?
Like many intelligent people, Gumbel did not understand the
numerical results.
Gulf War What?
In 1996 the New England Journal of Medicine published a
compilations of studies. Involving tens of thousands of veterans who served in
the Persian Gulf compared to veterans of comparable age who did not serve
there. The study found no
different death rates, hospitalization rates or rates of any self-reported
symptoms. When I heard this
reported on the news the announcer read the items and then said “but that does
not explain why Gulf War veterans have so many unexplained problems.”
I was barely able to refrain from throwing my shoe at the
television. The study showed there were no differences between the groups of
veterans on symptoms that have been called “Gulf War Syndrome.” Note: this does not mean that any particular
person who describes himself/herself as having the syndrome is exaggerating or
is not really ill.
Which end of the telescope do we look though?
Alan Dershowitz during the OJ Simpson trial wrote to the LA
Times and noted that although Mr. Simpson might have abused his wife, in any
given year roughly 1,500 women are murdered by a current or former abusive
spouse while there are 2 to 4 million spousal assaults. The odds of an abuser being a killer
were roughly one in a thousand.
Problem? Nicole Simpson was murdered. Dr. Kevin Hays started from that fact and found that in 1992
of 890 murders of women who had been abused, 715 were killed by their
abusers. These odds were roughly
80 out of 100. How the question is
asked makes a gigantic difference.
Numbers have different meaning based on what they are used
for. One common use is for identification. Your address, phone number and social security number are
examples. Add together the social
security numbers of everyone in your family, divide by the number of people in
your family and you get …a meaningless number.
Absolute numbers are sums, e.g. there are 25 students
enrolled in a class.
Numbers can be used to find percentages. 45% of students in a class are
male.
Numbers can also be used for measurement. When a nurse or a
doctor asks —Are you in pain?
On a scale of 0 to 10 with 0 being no pain at all and 10 being the worst
pain imaginable how would you rate your pain? You give a number that can be compared with your answer to
that exact question in the past or in the future. It doesn’t matter that your 4 would be an 8 for me. (I’m a wimp.) There is no possible meaning to comparing different people
on that question but the scale is surprisingly helpful with a single person.
Wanna’ Bet?
Numbers can be used to calculate odds. If you flip an
unbiased coin chances are that on any one flip it will come up heads is 50% and
chances it will come up tails is 50%.
If I flip an unbiased coin nine times and it comes up heads nine
times. The odds of it coming up
head on the next flip is …50%; the odds of it coming up tails is also 50%.
“Gambler’s error” is thinking that any set of past random results will effect
the next random event in a sequence.
For scientific research to be used as evidence in federal
court it must meet Daubert Standards
1) the
testing and technique must be reliable (testing and retesting scores of the
same people over a short period of time should be similar)
2) must
be capable of showing the finding is wrong (which is why intelligent design is
not a scientific theory)
3) published
and peer reviewed (subject to criticism by knowledgeable people)
4) known
or potential error rate (no measurement is perfect)
5) generally
accepted by the scientific community
6) have
sufficient data; generally more is better (to calculate the odds of an unbiased
flipped coin coming up heads 10,000 flips is more likely to be accurate than 10
flips.)
7) relevant
to the court case in question
I could go on but I suspect the odds of you continuing to
find this interesting are decreasing.
Have you learned anything?
When have you noticed misunderstanding of numbers?
