-- DianeKolb - 11 May 2009

Department of Biostatistics Seminar/Workshop Series

Sample Size Adjustments - It's About More Than A Formula

Rafe Donahue, PhD

Associate Director Statistics, BioMimetic Therapeutics, Inc. & Adjunct Faculty, Department of Biostatistics, Vanderbilt University School of Medicine

Wednesday, May 20, 1:30-2:30pm, MRBIII Conference Room 1220

Intended Audience: Persons interested in applied statistics, statistical theory, epidemiology, health services research, clinical trials methodology, statistical computing, statistical graphics, R users or potential users

Adjusting sample sizes based on interim analyses in on-going clinical trials is a hot topic in statistical literature. There are oodles of plans and schemes concerning how to update sample sizes in on-going clinical trials, complete with all the bells and whistles about maintaining Type I error rates. But these formula-based methods can be naive and short-sighted; as with almost everything in the real world, "it's more complicated than that."

I will recount a true story of sample-size updates in a real-life clinical trial and discuss how the straight-forward statistical approach was inadequate. I will present a methodology that allows one to do unblinded early looks at the data and increase the sample size without suffering a Type I error penalty.

And, if time allows, I will present a demonstration of a Kelvin wheel-and-disk integrator (a mechanical analog computer that computes integrals) made entirely of Lego.
Topic revision: r2 - 26 Apr 2013, JohnBock

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