Question
General Validity Issues:
Describe the difference between systematic error and random error in terms of shooting at a target.
Why should consideration of validity take precedence over consideration of precision?
Describe an example in which the study population is not a subset of the source population. (Hint: STD clinic sample.)
Describe an example in which the study population is a subset of the source population. (Hint: Loss-to follow-up in a cohort study.)
If the source population differs from the study population, is it still possible that the study sample can provide an estimate of effect close to the target parameter in the source population? Explain.
Why can’t you assess external validity based on the design/results of a single study?
Source: 250B Problem Bank
