Re: [S] "Sums of squares", the taxonomy issue again.

Frank E Harrell Jr (
Wed, 29 Apr 1998 13:37:40 -0400

Alan Zaslavsky and Bert Gunter made some wonderful points. They made me
think of a few other things to add:

1. I believe that SAS Institute and pharmaceutical companies have driven the use of improper
F-tests much more than the FDA

2. As Bert hints at, I believe that we teach many incorrect approaches in graduate
schools. One of my pet peeves is the failure of most programs to address
overfitting and model validation, for example.

3. I've been a consultant to FDA for many years and have found that FDA
statisticians are flexible and current in their knowledge of methodology.
They know a good argument for using a different
statistical technique when they see one. Frequently, sponsors propose very
standard, vanilla methods in fear of what FDA statistical reviewers may think.
These fears are largely unjustified in my experience. At any rate, sponsors can
have their proposed methods pre-approved in most cases.

4. Paul Gallo, Assistant Director of Biostatistics at Novartis Pharmaceuticals has put
together a really nice paper that addresses center effects in multi-center randomized
trials. He is presenting the paper at the "Understanding, Applying and Not Misusing
the Mathematical and Statistical Techniques Used in Clinical Trials" conference in Reston,
Virginia tomorrow and Friday. Paul addresses some long-ignored issues such
as loss of power when using type III sums of squares. Paul's E-mail address is

Frank E Harrell Jr
Professor of Biostatistics and Statistics
Director, Division of Biostatistics and Epidemiology
Dept of Health Evaluation Sciences
University of Virginia School of Medicine

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