Question

You are concerned about the association between toxic wastesites and nervous system disorders. You identify 300 people whowere recently diagnosed with nervous system disorders inMassachusetts. You then randomly select a group of 300 healthyindividuals from Massachusetts, frequency-matching on age, sex, andcounty of residence. You find that of those with nervous systemdisorders, 210 have a large toxic waste site within a mile of theirhome. Of the healthy individuals, 170 live near a large toxic wastesite.

1. What kind of study is this?
   1. Concurrent cohort
   2. Retrospective cohort
   3. Case-control study
   4. Cross-sectional study

2. Calculate the appropriate measure of association betweentoxic waste site and nervous system disorders.

3. How do you interpret your results based on themeasurement?