Health Research?

Question for my health research class...








2. The major reason that the external validity of randomized clinical trials (RCTs) is sometimes not high is because (highlight correct response)


a. the sample size is often too small


b. study subjects are often highly selected and not representative of the general population


c. randomization doesn’t control for bias and confounding


d. the investigator may be biased to find a positive result





Im thinking letter B but am unsure. i think c and d are internal problems not external problems. help please.

Health Research?
Yes, I also go with B.


BUT many times a clinical trial


comes up empty-handed is also because of A. Just not


enough people were found to


make a credible trial.