## Group effects obsolete? [Two-Stage / GS Designs]

Dear Helmut!

» I have seen some FDA code a good while ago:

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Yep. Implementation of what is written in the letter.

But IMHO the RANDOM statement is superfluous since it doesn't do anything other than printing a symbolic representation of expected mean squares. If one is really interested in having a random effect for subj(seq*group)

» Followed by:

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Same wording in the letter I have.

But the most interesting part of my letter:

Can't imagine BE studies where this is not true, except multi-center studies, but these are rare for BE evaluation.

So what? Group effects are a Chimera?

» » BTW: Helmut, how had you planned the evaluation of the second stage, if it would be necessary?

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» Probably too naïvely:

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Too naïvely may be true .

» I have seen some FDA code a good while ago:

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`PROC GLM DATA = DATASET;`

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` CLASS SUB TRT PER SEQ GRP;`

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` MODEL Y = GRP SEQ SEQ*GRP SUBJ(SEQ*GRP) PER(GRP) TRT TRT*GRP /SS3;`

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` RANDOM SUBJ(SEQ*GRP);`

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` TEST H = SEQ GRP E = SUBJ(SEQ*GRP)/HTYPE=3 ETYPE=3;`

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` ESTIMATE 'T VS R' TRT 1 -1;`

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` LSMEANS TRT/STDERR PDIFF CL ALPHA=.1;`

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`RUN;`

Yep. Implementation of what is written in the letter.

But IMHO the RANDOM statement is superfluous since it doesn't do anything other than printing a symbolic representation of expected mean squares. If one is really interested in having a random effect for subj(seq*group)

`Proc MIXED`

should be used.» Followed by:

» ...

Same wording in the letter I have.

But the most interesting part of my letter:

*"If all of the following criteria are met, it may not be necessary to test for group effects in the model:*- the clinical study takes place at one site;

- all study subjects have been recruited from the same enrollment pool;

- all of the subjects have similar demographics; and

- all enrolled subjects are randomly assigned to treatment groups at study outset

Can't imagine BE studies where this is not true, except multi-center studies, but these are rare for BE evaluation.

So what? Group effects are a Chimera?

» » BTW: Helmut, how had you planned the evaluation of the second stage, if it would be necessary?

»

» Probably too naïvely:

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`fixed: sequence, treatment, stage, period, group,`

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` group × treatment, stage × treatment`

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`random: subject(sequence × stage)`

Too naïvely may be true .

—

Regards,

Detlew

Regards,

Detlew

### Complete thread:

- Potvin C in the EU Helmut 2013-04-16 17:40
- Potvin C in the EU ElMaestro 2013-04-17 02:31
- Potvin C in the EU Helmut 2013-04-17 12:23
- 2 Groups model FDA d_labes 2013-04-17 13:10
- 2 Groups model FDA Helmut 2013-04-17 16:37
- Group effects obsolete?d_labes 2013-04-18 09:55
- Group effects FDA/EMA Helmut 2013-04-19 14:34
- Group effects FDA/EMA mittyri 2014-08-21 15:34
- Group effects FDA/EMA ElMaestro 2014-08-21 17:31
- Group effects EMA mittyri 2014-10-01 11:25
- Group effects EMA ElMaestro 2014-10-01 11:31
- Group effects EMA Helmut 2014-10-01 13:24
- Group effects EMA VStus 2016-10-06 22:06
- Group effects EMA ElMaestro 2016-10-07 12:45
- Group effects EMA mittyri 2016-10-07 15:06
- Fixed effects model with Group term mittyri 2016-10-09 13:27
- Fixed effects model: changing the F, p values mittyri 2016-10-10 18:33
- Fixed effects model: changing the F, p values ElMaestro 2016-10-10 20:10
- Fixed effects model: changing the F, p values Helmut 2016-10-11 00:17
- Holy War of type III d_labes 2016-10-11 13:17
- Significance of Group effect in Russia: why the type III is so 'important' mittyri 2016-10-11 15:07

- Fixed effects model: changing the F, p values zizou 2016-10-11 01:06
- FDA group model in R mittyri 2016-10-11 13:43
- FDA group model in R ElMaestro 2016-10-12 01:07
- FDA group model in R VStus 2016-10-17 15:32
- FDA group model in R ElMaestro 2016-10-17 18:58
- FDA group model in R VStus 2016-10-20 13:57

- FDA group model in R ElMaestro 2016-10-17 18:58

- FDA group model in R mittyri 2016-10-11 13:43

- Fixed effects model: changing the F, p values ElMaestro 2016-10-10 20:10
- Fixed effects model with Group term VStus 2016-10-20 13:54

- Fixed effects model: changing the F, p values mittyri 2016-10-10 18:33

- Fixed effects model with Group term mittyri 2016-10-09 13:27

- Group effects EMA mittyri 2016-10-07 15:06

- Group effects EMA ElMaestro 2016-10-07 12:45

- Group effects EMA VStus 2016-10-06 22:06

- Group effects FDA/EMA zizou 2016-12-31 02:54
- Group effects FDA/EMA Helmut 2017-06-03 14:57

- Group effects EMA mittyri 2014-10-01 11:25

- Group effects FDA/EMA ElMaestro 2014-08-21 17:31

- Group effects FDA/EMA mittyri 2014-08-21 15:34

- Group effects FDA/EMA Helmut 2013-04-19 14:34
- 2 Groups model FDA hiren379 2013-08-22 14:32
- Homework Helmut 2013-08-23 11:53

- Group effects obsolete?d_labes 2013-04-18 09:55

- 2 Groups model FDA Helmut 2013-04-17 16:37

- 2 Groups model FDA d_labes 2013-04-17 13:10

- Potvin C in the EU Helmut 2013-04-17 12:23

- Potvin C in the EU ElMaestro 2013-04-17 02:31