Final answer:
The evidence from a case-control study may be stronger than that from a cohort study because case-control studies are more efficient for investigating rare or latent diseases, and can clearly show associations between exposures and diseases via comparative histories.
Step-by-step explanation:
An expert may find that the evidence from a case-control study is stronger than that from a cohort study for several reasons. Firstly, case-control studies are particularly useful for investigating rare diseases or diseases with a long latency period, as they are more efficient in terms of time and resources. Such studies may provide stronger evidence when they show a significant association between an exposure and a disease, as they compare individuals with the disease (cases) to those without the disease (controls), delving into their histories to uncover risk factors.
In contrast, a cohort study follows a group of people over time to see who develops the disease and who does not. While cohort studies can provide a sense of temporal sequence between exposure and disease, they can be expensive and time-consuming, and may not be ideal for studying rare diseases due to the need for large sample sizes and long follow-up periods.
An example of a successful case-control study is the early research on smoking and lung cancer conducted by Doll and Hill. This study showed a strong association between smoking and lung cancer, serving as a template for the strengths of case-control studies in identifying risk factors for diseases with long development periods. Meanwhile, one of the largest cohort studies, also done by Doll and Hill, followed British male physicians over 50 years to study the same link, providing comprehensive longitudinal data at a higher cost and effort.