Bioequivalence and Bioavailability Forum

Hi ElMaestro,

that’s strange. Let’s try to access all values by their (original) names.

library(PowerTOST)
sampleN.RSABE(CV=0.3, theta0=0.95)$design
NULL
sampleN.RSABE(CV=0.3, theta0=0.95)$alpha
[1] 0.05
sampleN.RSABE(CV=0.3, theta0=0.95)$CVwT
[1] 0.3
sampleN.RSABE(CV=0.3, theta0=0.95)$CVwR
[1] 0.3
sampleN.RSABE(CV=0.3, theta0=0.95)$theta0
[1] 0.95
sampleN.RSABE(CV=0.3, theta0=0.95)$theta1
[1] 0.8
sampleN.RSABE(CV=0.3, theta0=0.95)$theta2
[1] 1.25
sampleN.RSABE(CV=0.3, theta0=0.95)$n
[1] 27
sampleN.RSABE(CV=0.3, theta0=0.95)$power
NULL
sampleN.RSABE(CV=0.3, theta0=0.95)$targetpower
NULL
sampleN.RSABE(CV=0.3, theta0=0.95)$nlast
[1] 27

sampleN.TOST(CV=0.3, theta0=0.95)$design
NULL
sampleN.TOST(CV=0.3, theta0=0.95)$alpha
[1] 0.05
sampleN.TOST(CV=0.3, theta0=0.95)$CV
[1] 0.3
sampleN.TOST(CV=0.3, theta0=0.95)$theta0
[1] 0.95
sampleN.TOST(CV=0.3, theta0=0.95)$theta1
[1] 0.8
sampleN.TOST(CV=0.3, theta0=0.95)$theta2
[1] 1.25
sampleN.TOST(CV=0.3, theta0=0.95)$n
NULL
sampleN.TOST(CV=0.3, theta0=0.95)$power
NULL
sampleN.TOST(CV=0.3, theta0=0.95)$targetpower
NULL

We get some NULLs also from sample.RSABE(). Even more interesting calling a variable which does not exist (since R is case-sensitive). foo()$design gave NULL, but:

sampleN.RSABE(CV=0.3, theta0=0.95)$Design
[1] 2x3x3
Levels: 2x3x3

sampleN.TOST(CV=0.3, theta0=0.95)$Design
[1] 2x2
Levels: 2x2

In the functions of PowerTOST design is character variable, but Design is a 1-level factor:
is.factor(sampleN.TOST(CV=0.3, theta0=0.95)$Design)
[1] TRUE

I don’t get it.

❝ […] if I want the sample sizes I can also easily get them via [1,7] or [1,8] from the sample size object returned …

I suggest to use Sample.Nfoo()[["Sample size"]] instead. You can use it in all functions and the current indices are not carved in stone. If we introduce another variable before #7 or reorder variables in a future version of PowerTOST your code will not work any more.