Discussion:
Strengths and Weaknesses of a Dairy Farm Study
In the fall of 1974, MDPH epidemiologists conducted a study in which they collected interview, medical, and laboratory data from residents of quarantined dairy farms and from residents of an equal number of non-quarantined farms matched by geographic area and randomly selected from lists of dairy producers. Personal interviews were conducted with 298 participants: 165 from 25 quarantined farms and 133 from 25 non-quarantined farms. The interviewers collected detailed information regarding environmental exposures (including PBB) and medical history, with emphasis on changes in health since mid-1973. In 214 persons, physical examinations were performed, as well as electrocardiograms, standard clinical laboratory tests on blood and urine, and measurements of serum PBB level.
QUESTION: What are the particular strengths and potential weaknesses of this study design?