A study that looks backward in time, usually using medical records and interviews with patients who already have or had a disease.

Ex post analysis.

A clinical study design which attempts to draw conclusions about a treatment based on an analysis of patients who have previously been treated for varying periods of time.

The review and analysis of existing water-quality data to provide a historical perspective on the water quality in the Study Unit, to assess strengths and weaknesses of available information, and to evaluate initial implications for water-quality management and study design.

The Retrospective Analysis is the 1999 follow-up study to the 1994 Canadian Environmental Review of the Uruguay Round of the GATT.