## Selection of w and w* [Two-Stage / GS Designs]

Dear Helmut,

» ...

» Using the median of n.tot to define the weights from the sim’s was a – maybe too naïve – attempt. Other suggestions? Some regulatory statisticians prefer the first stage in a TSD to be like in a fixed sample design. For some combinations of n

As I already said, DUNO really.

» Example: CV 0.1, GMR 0.95, target power 0.80. Fixed sample design’s n 8 (n

»

If you were pesssimistic, so in the spirit of the MCT ist would be wise to choose the second pair of weights with decreased value. Or do I err here ("real" n2 lower than the pessimistic)?

If I'm right, possible values could be:

w=0.999, w*=0.5 (or something like that value)

Or we stay for that extremal case with the standard combination test?

But to state it again: For me it is a mystery how to choose the weights.

But I think it doesn't make so much difference if we are not totally wrong with our choosen weights.

As far as I have seen so far for a small number of examples: The power is influenced only to a "minor" extent. The TIE is controlled, whatsoever weights we choose.

» ...

» Using the median of n.tot to define the weights from the sim’s was a – maybe too naïve – attempt. Other suggestions? Some regulatory statisticians prefer the first stage in a TSD to be like in a fixed sample design. For some combinations of n

_{1}/CV in my grid this will be ≤ the median of n.tot. In other words, I’m not too optimistic but rather too*pessimistic*. Now what?As I already said, DUNO really.

» Example: CV 0.1, GMR 0.95, target power 0.80. Fixed sample design’s n 8 (n

_{1}⇒ 12 acc. to GLs). n.mean and median of n.tot 12 with the default weights (0.5, 0.25). Even the 95% percentile of n.tot is 12.»

If you were pesssimistic, so in the spirit of the MCT ist would be wise to choose the second pair of weights with decreased value. Or do I err here ("real" n2 lower than the pessimistic)?

If I'm right, possible values could be:

w=0.999, w*=0.5 (or something like that value)

Or we stay for that extremal case with the standard combination test?

But to state it again: For me it is a mystery how to choose the weights.

But I think it doesn't make so much difference if we are not totally wrong with our choosen weights.

As far as I have seen so far for a small number of examples: The power is influenced only to a "minor" extent. The TIE is controlled, whatsoever weights we choose.

—

Regards,

Detlew

Regards,

Detlew

### Complete thread:

- Finally: Exact TSD methods for 2×2 crossover designs Helmut 2018-04-21 17:17
- Exact TSD methods: Example Helmut 2018-04-21 20:33
- Finally: Exact TSD methods for 2×2 crossover designs ElMaestro 2018-04-21 20:49
- Flow chart (without details) Helmut 2018-04-21 21:41
- naive questions regarding new functions in Power2Stage mittyri 2018-04-28 15:54
- Some answers Helmut 2018-04-28 17:29
- Some more "answers" d_labes 2018-04-29 21:11
- clarification regarding user Power2Stage guides mittyri 2018-04-30 13:41

- naive questions regarding new functions in Power2Stage mittyri 2018-04-28 15:54

- Flow chart (without details) Helmut 2018-04-21 21:41
- Technicality: Weigths for the inverse normal approach d_labes 2018-04-25 14:19
- Selection of w and w* Helmut 2018-04-26 09:51
- Selection of w and w*d_labes 2018-04-26 20:02
- Now what? w & w* examples d_labes 2018-05-09 13:53
- Now what? w & w* examples Ben 2018-06-10 20:12
- Now what? w & w* examples Helmut 2018-06-11 13:57
- Now what? w & w* examples Ben 2018-06-12 19:14

- a bug in interim.tsd.in()? mittyri 2018-06-11 23:27
- a bug in interim.tsd.in()? Ben 2018-06-12 19:32
- Nonbinding futility rule d_labes 2018-06-13 16:59
- Bad weather? Helmut 2018-06-13 19:23
- NLYW? d_labes 2018-06-14 10:18

- Nonbinding futility rule Ben 2018-06-13 20:26
- Nonbinding futility rule d_labes 2018-06-14 10:47
- Nonbinding futility rule Ben 2018-06-15 17:58
- Binding / Nonbinding futility rule - alpha control d_labes 2018-06-16 19:42
- Binding / Nonbinding futility rule - alpha control Ben 2019-03-30 09:52

- Binding / Nonbinding futility rule - alpha control d_labes 2018-06-16 19:42

- Nonbinding futility rule Ben 2018-06-15 17:58

- Nonbinding futility rule d_labes 2018-06-14 10:47

- Bad weather? Helmut 2018-06-13 19:23

- Nonbinding futility rule d_labes 2018-06-13 16:59

- a bug in interim.tsd.in()? Ben 2018-06-12 19:32

- Now what? w & w* examples Helmut 2018-06-11 13:57

- Now what? w & w* examples Ben 2018-06-10 20:12

- Selection of w and w* Helmut 2018-04-26 09:51