Question

In epidemiology, an ecological study refers to research

a. in which exposure data are available for groups but not for their individual members

b. in which exposure is measured prior to outcome

c. on how changes in an ecosystem affect spread of a contagious disease

d. on host species and other ecologic reservoirs for infectious organisms

on how changing demography of a population affects the distribution of chronic disease

Answer 1

Correct Answer- a. in which exposure data are available for groups but not for their individual members

A study in which at least one variable, either an exposure or the outcome, is measured at the group (not individual) level. Examples of group-level measures include the incidence rate of cancer among a specific population, the meanlevel of blood pressure of patients seen at a clinic, the average sunlight exposure at specific geographic location on the earth, or even a preventive service included in a health insurance plan. The occurrence of disease is compared between groups that have different levels of an exposure, which affords this study design to have at least one comparision group.