A randomized, double-blinded trial finds that oral corticosteroids are superior to placebo in hastening the resolution of otitis media with effusion. Possible reasons why this study, might have given a falsely positive result include:
|A||The sample size may have been too small|
|B||The apparent effect might be a result of chance|
|C||Lax inclusion criteria may have led to inclusion of some subjects in the study who did not really have otitis media with effusion|
|D||None of the above|
a. As a general rule, it is much easier to get a falsely negative result on a randomized blinded trial than a falsely positive result. The reason is that errors will tend to affect both treatment groups, making it harder to show a difference between them.
b. Thus, in this question, inclusion of subjects without the ear effusion (who could not benefit from the intervention) and incorrect determination of which effusions resolved, would both lead to falsely negative, not falsely positive results. Similarly, a small sample size is a reason for a falsely negative, but not a falsely positive result. Double blinded trials are studies where both the subject and the observer are blinded to the treatment.
c. Only chance (random error), a breakdown in the blinding or randomization process, or a differential loss to follow-up would be causes of a falsely positive result.