In article <8s8egf$n5f$[EMAIL PROTECTED]>,
<[EMAIL PROTECTED]> wrote:
>In article <[EMAIL PROTECTED]>,
> Jerry Dallal <[EMAIL PROTECTED]> wrote:
>> (1) statistical significance usually is unrelated to practice
>> importance.
>I don't think so. I can think of many examples in which statistical
>inference plays an invaluable role in practical applications and
>instrumentation, or indeed any "practical" application of a theory etc.
>Not just in science, but engineering, e.g aircraft design, studying the
>brain, electrical enginerring. Certainly there are examples of
>statistical nonsense, e.g. polls, but i wouldn't go so far as to say it
>is usually like this.
>I *would* argue that without some method to determine the likelihood of
>a difference b/w two conditions you have no chance of determining
>practical importance at all.
>> (2) absence of evidence is not evidence of absence
>Everyone who has done elementary statistics is aware of this edict. But
>what if your power is very high and/or you have very large N? I have
>always found it surprising that we can't turn it around and develop a
>probability that two groups are the same. Power or beta is surely
>correlated with the certainty of this approach.
I believe you will find that most researchers in the sciences
accept the p-value as religion. In the report of the recent
British study on Type 2 diabetes, there was an effect which
was stated as "unimportant" because the p-value was .052.
The likelihood function contains all the information in the
data for the purpose of making a decision. Without having
extraneous information, like the sample size and which test
is being performed, and more, the p-value cannot be obtained
with any amount of work. And one needs even more to get the
likelihood function from the p-value.
--
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, Dept. of Statistics, Purdue Univ., West Lafayette IN47907-1399
[EMAIL PROTECTED] Phone: (765)494-6054 FAX: (765)494-0558
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