Principles
The goal of this principle is to minimize selection bias. Requires that controls are representative of group but not necessarily the general population.
Study Base Principle
Can occur when information is collected by an observer who knows the case-control status or hypothesis under study
Interviewer Bias
Use a primary study base and ensures that controls are drawn from the same source as the cases.
Population Controls
Can learn information about the exposure distribution
Advantage of Population controls
Less motivated to be in the study which can lead to high nonresponse rates.
Disadvantage of Population controls
The goal of this principle is to minimize the effect of confounding on the estimate of effects while also avoiding over-matching.
The Deconfounding Principle
Cases and controls report exposure with equal inaccuracy
Report Bias (AKA non-differential misclassification)
A good way to get healthy controls when the study base is not well defined.
Neighborhood Controls
- Controls likely to be from the same study base
- Easy and cheap
- Less prone to recall bias
Advantages of Hospital controls
- Potential for overmatching
- More prone to selection bias
- Controls may not represent exposures in the study base population
Disadvantages of Hospital controls
The goal of this principle is to maximize the information for fixed expenditure of time and money. But may conflict with other principles.
The Efficiency Principle
Define differential reporting bias
Cases and controls report exposure with unequal inaccuracy (AKA Recall bias)
Similar to hospital controls but healthier.
Medical practice controls
- Convenient
- Cheap
- Higher motivation and response rate
- Can control for genetics or environment
Advantages of Relative controls
People who are outgoing are more likely to participate in the study.
Friendly control bias
What is the difference between a primary study base and a secondary study base?
A primary study base is when the study base is defined before ascertainment of cases, while a secondary study base case ascertainment is defined first before the study base is identified.
How does differential reporting bias mainly happen?
Cases remember exposure better than controls
Motivated by the deconfounding principle and not the study base principle.
Relative Controls
- Less prone to recall bias
- Less prone to interviewer bias
- Similar motivation and response rates as cases
- Cheap
Disease Registry controls
Which types of controls are more prone to overmatching?
Hospital controls, Friend controls, relative controls
The goal of this principle is to minimize information bias. The degree of accuracy of measuring various exposures of interest should be equivalent in cases and controls.
The Comparable Accuracy Principle
Which type of study is most prone to recall bias?
A. Randomized clinical trial
B. Retrospective cohort
C. Prospective cohort
D. Case - control study
Case control study
Used as a surrogate for matching on neighborhood, age, social class, education and other characteristics
Friend controls
- Convenient
- Cheap
- Higher motivation and response rate
Advantages of Friend controls