Kudos! [Power / Sample Size]

posted by ElMaestro  – Belgium?, 2017-02-05 21:15  – Posting: # 17016
Views: 19,809

Hi Hötzi,

» Quick & extremely dirty:
» library(PowerTOST)
» 100*power.TOST(alpha=0.5, CV=0.3, theta0=0.95, n=40, theta1=0.8, theta2=1)-1.25
» # [1] 76.57964


I can't follow this, alpha 0.5? Substraction of 1.25% somehow from ... what?

Instead, I propose something along the lines of:

pwrDK222BE=function(alpha, CV, theta0, theta1, theta2, n)
{
  ##power the standard way is P(GMR is below theta2)-P(GMR is below theta1)
  ##and thus we just plug in upper or lower= 1 to get us what we need.
  P= power.TOST(alpha=alpha, CV=CV,
       theta0=theta0, n=n, theta1=theta1, theta2=theta2)
  Plow= power.TOST(alpha=alpha, CV=CV,
        theta0=theta0, n=n, theta1=theta1, theta2=1.0) 
  Phi  =power.TOST(alpha=alpha, CV=CV,
       theta0=theta0, n=n, theta1=1.0, theta2=theta2)
  return(P-Plow-Phi)
}

pwrDK222BE(0.05, 0.3, 0.95, 0.8, 1.25, 40)


[1] 0.7652256

I could be wrong, but...

Best regards,
ElMaestro

"Pass or fail" (D. Potvin et al., 2008)

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