- Selective cases in a case-control study: clearly for exclusion and inclusion criteria, The sources of cases, Characteristics are similarly or matching
- Selection of controls in a case-control study: group of people without disease (controls), Characteristics are similarly, matching like cases
Advantages:
1. Only realistic study design for uncovering etiology in rare diseases
2. Important in understanding new diseases
3. Commonly used in outbreaks investigation
4. Useful if inducing period is long
5. Relatively inexpensive
Disadvantages:
1. Susceptible to bias if not carefully designed
2. Especially susceptible to exposure misclassification
3. Especially susceptible to recall bias
4. Restricted to single outcome
5. Incidence rates not usually calculate
6. Cannot assess effects of matching variables
Outcome measures of case-control studies
- Incidence rate (IR)
- Incidence relative risk (IRR)
- Odd ratio