libaiyi
★

China,
2018-06-28 11:47

Posting: # 18988
Views: 1,263

## How to calculate the sample size when we have 3 treatments? [Software]

Dear all,

I want to know how to calculate the sample size when there exists R, T1, T2 under 3*3 or 6*3 design?
Is there any software or R package available for statistical analysis of william design or 3*3 design when there exists R, T1, T2?

Helmut
★★★

Vienna, Austria,
2018-06-28 12:57

@ libaiyi
Posting: # 18989
Views: 1,147

## Sample size estimation: PowerTOST

Hi libaiyi,

» Is there any R package available for statistical analysis of william design or 3*3 design when there exists R, T1, T2?

The function sampleN.TOST() of package PowerTOST. After installing/attaching in the R-console or the command window of R Studio type known.designs() to see what is covered. In sampleN.TOST() use the argument design (i.e., design="3x6x3" for the six-sequence Williams’ design or design="3x3" for the Latin Square).
For low to moderate CVs sample sizes will be identical.

Cheers,
Helmut Schütz

The quality of responses received is directly proportional to the quality of the question asked. ☼
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d_labes
★★★

Berlin, Germany,
2018-06-28 13:30

@ libaiyi
Posting: # 18990
Views: 1,138

## Sample size for 3 treatments

Dear libaiyi,

additional to what Helmut has recommended:
Calling sampleN.TOST() with argument design="3x6x3" is appropriate if you aim for analyzing the data according to the "all at once" strategy.

If you analyze according to the "two at a time" strategy use design="2x2", the default for that argument.

Regards,

Detlew
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