An epidemiologist must have a clear definition of a disease to be sure the study participants are actually presenting with the specific disease of interest. If the disease is fairly nonspecific, meaning not every patient with the disease has the same symptoms, and symptoms can overlap with many other types of diseases, then it is best to include: (select BEST answer)

An epidemiologist must have a clear definition of a disease to be sure the study participants are actually presenting with the specific disease of interest. If the disease is fairly nonspecific, meaning not every patient with the disease has the same symptoms, and symptoms can overlap with many other types of diseases, then it is best to include: (select BEST answer)