Canada: subject, not period [Outliers]

posted by lechia – C of U, 2013-08-07 17:46 (3590 d 03:07 ago) – Posting: # 11238
Views: 9,755

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

Took some time to actually find where I could edit my profile, but I did read "the rules". :-)

❝ ❝ 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.

What I mean is that even though we have 3 periods and 3 treatments, the comparisons are Test 1 vs. Ref and Test 2 vs. Ref. In other words, we "ignore" one period when comparing the two.

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

True, however, whoever prepared the guidance most likely thought about a 2x2 study, where removal of one period "removes" the entire subject from analysis. It's unusual to have two (or more) products being tested as in my example. I guess you're right, however, in that removal of the entire subject from analysis will follow the guidance to the letter and perhaps it's not our place to try to figure out what the agency was thinking when writing the guidance.

To answer El Maestro's questions, Health Canada requires an outlier test to be done (before actually running the stats so that an outlier is removed or not without being affected by the study failing or not). Also, this doesn't pertain to a specific study, but rather I'm thinking of the best way to deal with this if/when it comes up, so the appropriate text can be added to the protocol a priori.

We're using PROC MIXED anyways.

Thanks to all for your input.

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