Two at a Time? Or All at Once? [Software]

posted by Helmut Homepage – Vienna, Austria, 2013-08-10 15:52 (3579 d 06:12 ago) – Posting: # 11260
Views: 15,939

Hi John,

❝ We actually spoke with FDA about the pool variance effect (at a conference) and they didn't seem to care. […]

I found the abstract of a 15 minutes presentation from the 2004 ENAR Spring Meeting of the IBS. Since it is so short below in all its splendor:

Donald J. Schuirmann, U.S. Food and Drug Administration

Suppose we have a bioequivalence study with three treatments – A, B, and C – and the objective of the study is to make pairwise comparisons among the treat­ments. Suppose further that treatment C is different in kind from A and B, so that the assumption of homogeneous variance among the three treatments is ques­tionable. One way to do the analyses, under normality assumptions, is Two at a Time – e.g., to test hypotheses about A and B, use only the data from A and B. Another way is All at Once – include the data from all three treatments in a single analysis, making pairwise comparisons within this analysis. If the assump­tion of homogeneous variance is correct, the All at Once approach will provide more d.f. for estimating the common variance, resulting in increased power. If the variance of C differs from that of A and B, the All at Once approach may have reduced power or an inflated type I error rate, depending on the direction of the difference in variances. I will attempt to quantify the difference between the two approaches for both the comparison of A to B and the compa­rison of A or B to C. Both parallel and crossover designs will be considered.

e-mail: [email protected]

Dif-tor heh smusma 🖖🏼 Довге життя Україна! [image]
Helmut Schütz

The quality of responses received is directly proportional to the quality of the question asked. 🚮
Science Quotes

Complete thread:

UA Flag
 Admin contact
22,616 posts in 4,740 threads, 1,610 registered users;
18 visitors (0 registered, 18 guests [including 9 identified bots]).
Forum time: 22:04 CEST (Europe/Vienna)

Do not worry about your difficulties in mathematics.
I can assure you mine are still greater.    Albert Einstein

The Bioequivalence and Bioavailability Forum is hosted by
BEBAC Ing. Helmut Schütz