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RegisterReplicate Designs & IntraSubj CV [General Statistics]
posted by Helmut 
– Vienna, Austria, 2011-04-28 17:00 (5543 d 02:28 ago) – Posting: # 6965
Views: 13,965
Dear randombadger!
Can you be a little be more specific? In some designs it’s possible to calculate CVs for both treatments, and in others not. FDA’s model for the commonly used partial replicate [TRR|RTR|RRT] is overspecified – you may get a number for CVWT, but only with a SAS-warning and being nonsense (since T is not replicated). Examples of 3-period replicate designs allowing estimation of both CVs are [TRT|RTR] or [TRT|RTR|TRR|RTT]. So which design do you have?
Almost. You should use
Can you ask them for a reference for their code?
Carryover should go the statistical waste-bin. Stephen Senn devoted (almost) an entire book to this topic.
❝ I have a 3 period, 2 treatment XO design and would like to calculate the intra-subject CV for the two treatments.
Can you be a little be more specific? In some designs it’s possible to calculate CVs for both treatments, and in others not. FDA’s model for the commonly used partial replicate [TRR|RTR|RRT] is overspecified – you may get a number for CVWT, but only with a SAS-warning and being nonsense (since T is not replicated). Examples of 3-period replicate designs allowing estimation of both CVs are [TRT|RTR] or [TRT|RTR|TRR|RTT]. So which design do you have?
❝ According to FDA guidance, […]
Almost. You should use
ddfm=satterth (Satterthwaite’s degrees of freedom) – not ddfm=kr (Kenward-Rogers); though I guess there shouldn’t be too much of a difference in results.❝ however I see my colleagues are using the following: […]
Can you ask them for a reference for their code?
❝ My colleagues also included a carryover in the model but I believe the washout periods are long enough hence not required.
Carryover should go the statistical waste-bin. Stephen Senn devoted (almost) an entire book to this topic.
—
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Helmut Schütz
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Dif-tor heh smusma 🖖🏼 Довге життя Україна!
Helmut Schütz
The quality of responses received is directly proportional to the quality of the question asked. 🚮
Science Quotes
Complete thread:
- Replicate Designs & IntraSubj CV randombadger 2011-04-28 13:02 [General Statistics]
![[Mix]](https://static.bebac.at/img/mix.png "open in Mix view")
- Replicate Designs & IntraSubj CVHelmut 2011-04-28 15:00
- Replicate Designs & IntraSubj CV randombadger 2011-04-28 15:25
- Replicate Designs & IntraSubj CV Helmut 2011-04-28 17:09
- Inter-subject dance with the wolves d_labes 2011-04-29 11:33
- How many subjects? jdetlor 2011-05-02 18:21
- G matrix d_labes 2011-05-03 08:26
- G matrix ElMaestro 2011-05-03 09:15
- G matrix d_labes 2011-05-03 09:51
- Results randombadger 2011-05-03 12:03
- Results - comments d_labes 2011-05-03 14:32
- Results - comments randombadger 2011-05-03 16:53
- Lost cents d_labes 2011-05-04 08:07
- Results - comments randombadger 2011-05-03 16:53
- Results - comments d_labes 2011-05-03 14:32
- G matrix ElMaestro 2011-05-03 14:16
- Results randombadger 2011-05-03 12:03
- G matrix d_labes 2011-05-03 09:51
- G matrix jdetlor 2011-05-03 19:37
- G matrix ElMaestro 2011-05-03 09:15
- G matrix d_labes 2011-05-03 08:26
- How many subjects? jdetlor 2011-05-02 18:21
- Replicate Designs & IntraSubj CV randombadger 2011-04-28 15:25
- Replicate Designs & IntraSubj CVHelmut 2011-04-28 15:00
Ing. Helmut Schütz