Ratio calculation of fully replicate study [RSABE / ABEL]

posted by Helmut Homepage – Vienna, Austria, 2020-07-09 14:19 (935 d 18:12 ago) – Posting: # 21662
Views: 3,194

Hi Mithu,

❝ ❝ Without knowing your SAS code it would be reading tea leaves.


❝ We have used Progesterone program.


… which nowhere gives the subject’s T/R-ratios.

❝ ❝ $$x/y=\exp (\log_{e}x-\log_{e}y)\;\left\{x,y \in \mathbb{R}^{+} \right\}\; {\color{red}{\neq}}\log_{e}x/\log_{e}y$$

❝ Still I could not understand.


Calculating the ratio of logs (2. of your OP) is nonsense.
The individual averaged log-differences \(I_{ij}\) (for subject \(i\) in sequence \(j\)) are computed in the FDA’s SAS macro by

ilat=0.5*(lat1t+lat2t-lat1r-lat2r);

Simply back-transform them.

Let’s have a look at the EMA’s full replicate reference data set:

SUBJECT   DATA  FORMULATION  PERIOD  SEQUENCE  logDATA 
   1    2285.96      R          1      BABA    7.734541
   1    1955.82      T          2      BABA    7.578565
   1    1345.94      R          3      BABA    7.204848
   1    2856.24      T          4      BABA    7.957261

Then$$\overline{I_{11}}=0.5\times(7.578565+7.957261-7.734541-7.204848)=0.2982185$$and$$\overline{T_{11}/R_{11}}=\exp \overline{I_{11}}=\exp 0.2982185=1.347456$$Confirmed by Phoenix WinNonlin’s RSABE-template and my pocket calculator. :-D

Which leaves my second question open:

❝ ❝ Why on earth do you want to use Excel?


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