Parallel designs (total variance) [Power / Sample Size]

posted by Nav Coelho – 2007-07-20 20:38 (5917 d 20:39 ago) – Posting: # 918
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(edited by Jaime_R on 2007-07-20 22:51)

Thanks for your response Helmut.

Well, I am not sure how to estimate the sample size for a parallel design? The formula that I am using uses inter-subject variability and the reference is attached (Tutorial in Biostatisitcs: Sample sizes for clinical trials with Normal data by Steven A. Julious). Formula is on page 1970 #69. But how would you get the inter-subject variability from the ANOVA for parallel design in order to calculate the sample size. Thanks for the reference, I'll take a look.

Re: 60% of inter to estimate the intra: I am a statistician and I routinely see the PK individuals taking 60% of inter to be the intra for estimating sample size for a crossover design and always wondered about the validity of the approach.

Appreciate your feedback!
Nav

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Edit: Full quote removed. Please see this post! [Jaime]

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