Bioequivalence and Bioavailability Forum

Hi Mohamed,

first of all, please read this post and follow the forum’s policy (you confirmed with the registration that you have read and accepted it)! I had to edit all of your posts…

❝ […] However, I found a SAS report that generate a Non parametric analysis test on Ln transformed Tmax;

t_max comes from an ordinal scale and therefore, follows a discrete distribution (dependent on the sampling schedule). Hence, a nonparametric analysis is correct in principle. However, transformations are only allowed for data coming from a ratio scale (continuous with a true zero point).
Therefore, the report you found is crap. SAS is a fine piece of software but only as good as the user. This one probably was not qualified for his/her job.

Common language will give you a hint whether an additive model (raw data) or a multiplicative model (log-transformed data) should be used. Every time you say “X is Y% of Z” or “X is Y% lower than Z” you should apply a log-transformation (e.g., C_max). If you say “the difference of X to Z is Y” you should use the raw data (e.g., t_max).