statistical analysis of William's Design [Study As­sess­ment]

posted by Helmut Homepage – Vienna, Austria, 2022-02-11 20:07 (826 d 11:40 ago) – Posting: # 22774
Views: 2,486

Hi Ahmed,

❝ […] William's design (3 treatment, 3 period, 6 sequence), 2 test products against one reference. I analyzed the data as 3-way, and also separated the test products, each with a reference, and analyzed them. My question: should I get the same result?

Extremely unlikely. In the separate evaluations (as Incomplete Block Designs) you get two estimates of the within-subject variances (one in the comparison of T1 vs R and the other in the comparison of T2 vs R). Even if they would be identical, you have different degrees of freedom in the analyses. In each of the IBDs you have \(\small{df=n-2}\) and in the pooled ANOVA \(\small{df=2\times n-4}\), where \(\small{n}\) is the total number of subjects. Although the point estimates might be the same, the confidence intervals will not.

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
23,029 posts in 4,834 threads, 1,641 registered users;
44 visitors (0 registered, 44 guests [including 6 identified bots]).
Forum time: 08:47 CEST (Europe/Vienna)

The most erroneous stories are those we think we know best–
and therefore never scrutinize or question.    Stephen Jay Gould

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