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RegisterType III SS again [🇷 for BE/BA]
posted by yjlee168 
– Kaohsiung, Taiwan, 2009-09-07 20:08 (5763 d 02:35 ago) – Posting: # 4159
Views: 13,205
Dear Elmaestro,
Because each subject just has one and the only one seq in a crossover study, so subj:seq is just the same as subj. However, it is interesting to find out that R treats the model of (lnAUC ~ seq + prd + trt + subj) and the other model of (lnAUC ~ seq + prd + trt + subj:seq) sightly differently through drop1() function to calculate type III SS that we've already had many discussion when we announce bear at this Forum.
As far as I know, for a balanced 2x2x2 crossover study, the SAS-calculated type III SS should be the same as the type I SS. Both should be the same as those calculated by R's drop1(). You said they're different. Could you explain more? Thanks.
Indeed.
❝ [...] It always will be when the single-term-deletion strategy is followed. This is because the model without Sequence as a factor includes Subjects. The subjects are "nested in sequence" (no pun intended!), so your sequence effect becomes effectively zero* (or to say it differently: you cannot [...]
Because each subject just has one and the only one seq in a crossover study, so subj:seq is just the same as subj. However, it is interesting to find out that R treats the model of (lnAUC ~ seq + prd + trt + subj) and the other model of (lnAUC ~ seq + prd + trt + subj:seq) sightly differently through drop1() function to calculate type III SS that we've already had many discussion when we announce bear at this Forum.
❝ [...] odd stuff for nested data. R does it un critically, SAS does some clever work for you, and therefore the SAS type III output differs from R's drop1 output.
As far as I know, for a balanced 2x2x2 crossover study, the SAS-calculated type III SS should be the same as the type I SS. Both should be the same as those calculated by R's drop1(). You said they're different. Could you explain more? Thanks.
❝ [...] the actual Sequence effect. Although I am not a fan of SAS, I totally agree on this specific issue.
Indeed.
—
All the best,
-- Yung-jin Lee
bear v2.9.2:- created by Hsin-ya Lee & Yung-jin Lee
Kaohsiung, Taiwan https://www.pkpd168.com/bear
Download link (updated) -> here
All the best,
-- Yung-jin Lee
bear v2.9.2:- created by Hsin-ya Lee & Yung-jin Lee
Kaohsiung, Taiwan https://www.pkpd168.com/bear
Download link (updated) -> here
Complete thread:
- Let's skip the fancy nesting syntax! ElMaestro 2009-08-26 20:54
![[Mix]](https://static.bebac.at/img/mix.png "open in Mix view")
- Let's skip the fancy nesting syntax! yjlee168 2009-08-26 22:29
- Let's skip the fancy nesting syntax! ElMaestro 2009-08-26 22:46
- Let's skip the fancy nesting syntax! yjlee168 2009-08-27 20:54
- Let's skip the fancy nesting syntax! ElMaestro 2009-08-27 22:14
- Let's skip the fancy nesting syntax! yjlee168 2009-08-27 20:54
- Let's skip the fancy nesting syntax! ElMaestro 2009-08-26 22:46
- Let's skip the fancy nesting syntax! yjlee168 2009-08-27 22:26
- Let's skip the fancy nesting syntax! ElMaestro 2009-08-27 22:46
- Simple solution ElMaestro 2009-08-27 23:53
- Simple solution yjlee168 2009-09-07 01:53
- Type III SS again ElMaestro 2009-09-07 15:47
- Type III SS againyjlee168 2009-09-07 18:08
- Type III SS again ElMaestro 2009-09-07 19:53
- Type III SS againyjlee168 2009-09-07 18:08
- Type III SS again ElMaestro 2009-09-07 15:47
- Simple solution yjlee168 2009-09-07 01:53
- Let's skip the fancy nesting syntax! yjlee168 2009-08-26 22:29
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