known.designs() [General Sta­tis­tics]

posted by Helmut Homepage – Vienna, Austria, 2018-03-09 16:42 (2293 d 20:01 ago) – Posting: # 18513
Views: 5,155

Hi Louis,

❝ I thought about the 'paired' design as I looked into known designs(), but I was not sure.

You were guessing right.

❝ […] in several instances it happens that in period 1 a subject receives what is called the 'probe' while in period 2 it receives the "probe+investigational drug".

Designed without consulting a statistician? Lacking period effects is a strong assumption.
The only designs where a paired design is common is assessing linear PK of a new drug. Such a study starts with a single dose followed by saturation and another profile in (pseudo) steady state. Then we compare AUC0–τ (MD) with AUC0–∞ (SD). Performing such a study as a crossover would be a logistic nightmare. Never ever have seen one.

❝ I'm trying to find the CV intra associated with a particular "probe" based on DDI study in a published paper (no CV intra, just PE, CI, and N), as I need to use it in the sample size determination (precision only, no power) for a new DDI. Would 'paired' cover this situation?


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