Final answer:
The study described in the question is a case-control study, where individuals with a condition (cases) are compared to those without the condition (controls) to examine potential risk factors.
Step-by-step explanation:
The student's question is about determining the type of study an epidemiologist conducted to investigate the potential risk factors for big toe cancer in the Yukon Territory. The epidemiologist matched each person with big toe cancer to a control individual who did not have big toe cancer on the basis of daily activity, history of athlete's foot, and history of ingrown toenails. The methodology described here is characteristic of a case-control study, where patients with a particular condition (cases) are compared to individuals without the condition (controls) to see if there are significant differences in exposure to potential risk factors. This approach allows researchers to look backward in time to assess exposure to suspected risk factors, making it a retrospective study design.
Case-control studies are particularly useful when dealing with rare diseases, such as big toe cancer, because they are more efficient and less costly than cohort studies. They provide a way to measure the association between exposure (shoe size larger than 10 in this case) and disease (big toe cancer) by calculating odds ratios. It contrasts with a cohort study which is prospective and tracks participants forward in time to see who develops a disease.
Therefore, the type of study described by the student is a case-control study. This design is often employed by epidemiologists to investigate the associations between potential risk factors and specific health outcomes, especially when the health outcome is rare, as in the case of big toe cancer.