Following design is of which epidemiological study ?
Ans. is 'a' i.e., Case control study Case Control Studyo Case control study is a common first approach to test causal hypothesis,o Case - Case is an individual who has developed the disease.o Control - Is an individual who has not developed the disease but is otherwise comparable to case (e.g. age, sex, occupation, social status etc).o The case - control study has three distinct features -i) Both exposure (risk factor) and outcome (disease) have occurred before the start of study - so, there is no further risk for subjects.ii) Study proceeds backwards from effect to cause - retrospective study.iii) It uses a control or comparison group to support or refute an inference.Cohort Studyo Cohort study is a type of analytic observational study (like case control study).o Cohort study proceeds forward from cause to effect, i.e., disease has not occured in subjects (In contrast to case- control study which proceeds backward from effect to cause)o It is also known as Prospective study, longitudinal study, Incidence study, forward looking studyo The features of cohort studies arei) The cohorts are identified prior to the appearance of the disease under investigation.ii) The study groups, so defined, are observed over a period of time to determine the frequency of disease among them.iii) The study proceeds forward from cause to effect.o In case control studyi) Direction of study - Reverseii) Time - Forwardo In cohort studyi) Direction of study - Forwardii) Time- ForwardDesign of a Case-Control StudySchematic diagram of the design of case control and cohort studies Source (30A)
Case control study
Cohort study
Ecological study
Cross-sectional study
Epidemiological Study