Donald,
Sorry about the vagueness. You have answered my questions very
thoroughly. In response to your questions,
On 9 Jan 2000 21:42:51 -0800, [EMAIL PROTECTED] (Donald F.
Burrill) wrote:
>This still does not describe what you used the test ON. Were they simply
>pairwise comparisons (treatment 0 vs treatment 1, 0 vs 2, 0 vs 3, 1 vs 2,
>1 vs 3, 2 vs 3)? -- which is what Tukey's HSD is usually applied to.
> Or did they involve more complex contrasts, e.g.
> (treatment 0 + trtmt 2 + trtmt 3) vs 3*(trtmt 1)
I performed simple pairwise comparisons only, not complex contrasts.
>> (Drug A and Drug B columns are not used when I
>> performed post hoc analysis. Set (experimental set) is also excluded
>> during analysis, and is just here for illustration.
>
>Why is Set excluded? Looks like another between-subjects factor to me,
>and if so it ought to have been included in a three-way anova.
Actually, I included sets initially just to see if they were
important, but the p value for sets= 0.77, and my r^2 improved when I
removed this variable.
>> I know this is a relatively simple-minded approach, but it's the best
>> method I could come up with at the time. The fundamental question is
>> whether it is technically wrong to perform the analysis the way I did;
>> is this method I chose going to screw up my conclusions because the
>> analysis yields erroneous results ?
>
>What leads you to think the results are erroneous? Although you have
>been pretty fuzzy about what you actually did, and you have not reported
>nor described your results, you've provided no clear evidence of anything
>"technically wrong" (whatever that might mean).
I wanted to ask someone knowledgeable, to make sure that I am not
making a serious technical mistake in my analysis.
Most biologists are relatively weak in knowledge of math and
statistics. Data analysis is regarded as a plug and chug sort of
thing, and little attention is paid to the actual details of
statistical analysis. Biologists, for the most part, use whatever
common or simple stats package is available. Few biologists I am aware
of use randomized blocking designs or GLM approaches; even complicated
studies are often analyzed using nothing but Student-t tests.
You have said, "you may not be seeing all that there is to be seen in
this corner of the universe." I can tell you that use of inappropriate
statistical procedures is a large problem in the biological sciences,
and one I hope to avoid making.
So, even though I may not be seeing everything, my fears have been
laid to rest. Thanks very much for your help!
JE
