My watch list

Attrition bias

Attrition bias needs to be Wikified!
So here's what needs to be done:

Check if the article is a copyright violation or meets deletion criteria.

✔ check

Suggestion: Do a quick Google or Yahoo! search with a sentence from the article.

Check if another article already exists on this subject.

✔ check

Suggestion: Use the Wikipedia search to see what comes up.

Add Wikipedia markup.

✔ check

Suggestion: Read up on m:Help:Editing.

Format the article.

(pending)

Suggestion: Read up on Guide to Layout and Manual of Style.

Remove the {{wikify}} tag (if there is one).

(pending)

Join the Wikification effort! • How to use this template

Attrition bias or exclusion bias in epidemiology is a kind of selection bias caused by attrition of subjects.

This can be due to:

Systematic difference of participants in the study from the population from which they were selected due to selective loss of participants.

Systematic deviation of a measure of the effect of intervention from true value due to different attrition rate of subjects in the trial. Different loss of subjects in intervention and comparison group (e.g. withdrawals, dropouts, protocol deviators) may change the characteristics of these groups and outcomes irrespective of the studied intervention.