Re: Medical Research

In article <dmtag.3212$y4.1475@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
George Conklin <georgeconklin1@xxxxxxxxxxxxx> wrote:

"Herman Rubin" <hrubin@xxxxxxxxxxxxxxxxxxxx> wrote in message
news:e4d7t0$5pkg@xxxxxxxxxxxxxxxxxxxxxxx

You're too focused on stats.

Statistics is the science of decision making under
uncertainty. Is that not what patients are supposed
to be doing with the advice of the physician.

Certain uses of statistics have been called the "religion
of medicine". This includes the belief in "statistical
significance" and p-values.


Herman, only if the differences are very small, right? You are talking
about 3 out of 3 being cured. Maybe that would not significant, but 8 out
of 8 would be. I was involved with the evaluation of a noise lawsuit with
that kind of 'pretrail' determination by retired judges. It was settled at
that point without more suits. Both sides knew what was going to happen.

The place where I read this was 3 out of 3 rather than 7
out of 8. I did some calculations, and decided that I
would prefer the 3 out of 3 over the 7 out of 8 if I
expected the probability that this type of treatment would
work would be somewhat more that .9. This type of computation
is needed, and the prior input is needed.

BTW, the 7 out of 8 is statistically significant, but I
did not take that into account in my evaluation. If this
time of treatment, if any good at all, was likely to work
in 95% of the cases, the 3 out of 3 would be the choice.

Statistics can only change the odds of the
various types of possibilities. The odds can become so
overwhelming that we may say something is proved.

In any case, the standard use of statistical significance
cannot even be translated directly into odds. That null
hypothesis is always false; how much water one drinks has
an effect on diabetes or cancer, which is probably small.
Statistical significance says absolutely nothing about the
magnitude of the effect, nor does its lack.

Whether a treatment is good is not changed by collecting
data, and intelligent decision making will cause the use of
many treatments before that much information is present.

....................

This is the case; things like this were the reason why
one cannot just look at a study and see what else comes
out. However, one can do much more than is being done
now, but nowhere near what we would like.

We need better studies, and more data collected on each
study.

Absolutely.

<> <> Continuous variables should be used as such, and
<> <> models based on biology used more often. All of the
<> <> studies I have seen on the use of statins are horribly
<> <> flawed; they do not take into account the actual
<> <> concentrations of the various lipids. As of this time,
<> <> there is not a single reasonable study showing that the
<> <> use of a low fat diet is beneficial.

.........................

<> <> Everyone needs to understand the concepts of probability
<> <> and statistical decision theory, but they do not need to
<> <> know how to carry out the calculations. Problems need to
<> <> be formulated first.

You are right Herman. As genetics move faster, we are going to have to
mine old studies for new results because the old hypotheses are going to
seem quaint, but the records of experiments will remain.




--
This address is for information only. I do not claim that these views
are those of the Statistics Department or of Purdue University.
Herman Rubin, Department of Statistics, Purdue University
hrubin@xxxxxxxxxxxxxxx Phone: (765)494-6054 FAX: (765)494-0558
.

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