In Prospective Cohort Studies, Why Is Loss to Follow‐up a Source

Multiple Choice

In prospective cohort studies, why is loss to follow‐up a source of selection bias?

A) The study will no longer be representative of the general population
B) It reduces the size of the study sample
C) Those lost to follow‐up may have different characteristics to those who remain in the study
D) Those who are lost to follow‐up may recall things differently from those who remain in the study
E) There is more likely to be ascertainment bias when measuring outcomes in those who remain in the study