Translations:Advanced Field Epi:Manual 1 - Disease Investigation/257/en

A "case" group is selected from animals with the disease of interest and a "control" group is selected from animals without the disease. The presence or absence of possible risk factors are then measured for the two groups and compared. Case-control studies are well suited to rare diseases and many suspected risk factors can be compared at the same time. They are relatively quick and inexpensive to perform but are susceptible to many biases and do not allow estimation of disease frequency (prevalence or incidence).