Bioequivalence and Bioavailability Forum

Canada: subject, not period [Outliers]

posted by Helmut  – Vienna, Austria, 2013-08-07 15:48 (3913 d 21:46 ago) – Posting: # 11232
Views: 10,400

Hi Mac,

welcome to the club! You are one of the <1% of members editing their profile.

❝ Let's say I have a study where two products are tested against a reference (3 period, incomplete block).

I don’t understand what you mean by incomplete block when you tested three treatments in three periods. Generally in an IBD: treatments > periods.

❝ Test 2 product for one of the subjects is an outlier for AUC and Cmax as per protocol (>3 studentized residuals away from the mean).

❝

❝ The question is, should this subject be removed completely from the study or just the period in question?

Depends on what you have specified in the protocol. By removing one period you’ll end up with an incomplete data set which might be evaluated by a mixed effects model (SAS-speak: PROC MIXED). See also Senn’s quote in this post. Note that PROC GLM will always drop the entire subject even if you kept the other periods in the data set. Quite often CIs by PROC MIXED (incomplete data) are very close the the ones obtained by PROC GLM (imbalanced data). For an example see this post.

❝ From a statistical point of view, only one of the test products/periods was an outlier, however, I'm of the view that given that since we don't know what caused the "unusual" profile in the Test 2 profile, perhaps it's better to remove the subject altogether.

Likely. The Canadian guidance talks only about removal of outlying subjects, not observations.

—
Dif-tor heh smusma 🖖🏼 Довге життя Україна! 
Helmut Schütz


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Science Quotes

Complete thread:

• "Removal" of an outlier: subject vs period lechia 2013-08-06 23:23 
  • "Removal" of an outlier: subject vs period ElMaestro 2013-08-07 11:09
  • Canada: subject, not periodHelmut 2013-08-07 13:48
    • Proc GLM with missings d_labes 2013-08-07 14:46
      • Proc GLM with missings jag009 2013-08-07 15:03
      • Proc GLM with missings Helmut 2013-08-07 15:21
        • Proc GLM with missings ElMaestro 2013-08-07 15:39
          • Proc GLM with missings ElMaestro 2013-08-07 16:22
          • Proc GLM random d_labes 2013-08-07 16:46
        • Proc GLM with missings for 2x2 crossover d_labes 2013-08-07 16:34
    • Canada: subject, not period lechia 2013-08-07 15:46
      • Canada: subject, not period Helmut 2013-08-07 15:57
    • Canada: subject, not period lechia 2013-08-12 15:48