A major problem resulting from the lack of randomization in a cohort study is:
a. The possibility that a factor that led to the exposure, rather than the exposure itself, might have caused the disease
b. The possibility that a greater proportion of people in the study may have been exposed
c. The possibility that a smaller proportion of people in the study may have been exposed
d. That, without randomization, the study may take longer to carry out
e. Planned crossover is more likely
Answer: a. The possibility that a factor that led to the exposure, rather than the exposure itself, might have caused the disease