1932

Abstract

An ecologic study focuses on the comparison of groups, rather than individuals; thus, individual-level data are missing on the joint distribution, of variables within groups. Variables in an ecologic analysis may be aggregate measures, environmental measures, or global measures. The purpose of an ecologic analysis may be to make biologic inferences about effects on individual risks or to make ecologic inferences about effects on group rates. Ecologic study designs may be classified on two dimensions: whether the primary group is measured (exploratory vs analytic study); and whether subjects grouped by place (multiple-group study), by time (time-trend study), or place and time (mixed study). Despite several practical advantages of ecologic studies, there are many methodologic problems that severely limit causal inference, including ecologic and cross-level bias, problems of confounder control, within-group misclassification, lack of adequate data, temporal ambiguity, collinearity, and migration across groups.

Loading

Article metrics loading...

/content/journals/10.1146/annurev.pu.16.050195.000425
1995-05-01
2024-10-08
Loading full text...

Full text loading...

/content/journals/10.1146/annurev.pu.16.050195.000425
Loading
  • Article Type: Review Article
This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error