1. Mother and Child Health: Research Methods G.J.Ebrahim Editor Journal of Tropical Pediatrics, Oxford University Press.

2. Criteria to be fulfilled in Cohort Studies Observation must take place over a meaningful period of time All members of the cohort must be observed. Drop-outs distort the study.

3. Types of Cohort Past PresentFuture Concurrent Cohort Assembled now Followed into future Historical Cohort Assembled from past records Followed till now Retrospective Cohort Exposure and outcome

4. Advantages and Disadvantages of Cohort Studies Direct calculation of incidence Time sequence can be established Different outcomes for one agent can be determined Large numbers to be measured over a long time Subclinical disease may escape diagnosis Advantages Disadvantages

5. Analysis of Cohort Studies Exposed Time Diseased (n=39) Healthy Not exposed Diseased (n=6) Healthy n = 30 000 n = 60 000