Contents
How do you select a comparison group?
There are two key things that are essential in selecting the comparison group in a cohort study: The unexposed (or less exposed) comparison group should be as similar as possible with respect to other factors that could influence the outcome being studied (possible confounding factors).
What is a control group for comparison?
Control group: In an experiment, the group of individuals who do not receive the treatment or intervention is called the control group. A true control group only exists if random assignment was done properly. If no random assignment was done, then the group is called a comparison group.
What is a good comparison group?
A good comparison group should have substantial overlap with the treatment group in terms of the characteristics likely to affect program outcomes. Informed by the logic model, the evaluator should exercise judgment regarding the key characteristics that should be used to identify similar individuals.
Does a cohort study have a comparison group?
The lack of a comparison group is of particular importance for distinguishing cohort studies from case series because in many definitions, they share a main design feature of having a follow-up period examining the exposed individuals over time [2, 3].
What is an external comparison group?
External Comparison Group. When it isn’t possible to take a well-defined cohort and divide it into exposure groups, sometimes one can identify an external comparison cohort. This type of comparison group was used when researchers wanted to look at occupational exposure to disulfide in rayon factory workers.
Why do you need a matched comparison group?
Matched-Comparison Groups . The most important aspect of this research design is that an evaluator must identify two similar groups, one consisting of individuals who participate in the intervention (treatment group), and the other consisting of those who do not (comparison group). Because in most educational interventions the
How are treatment groups different from comparison groups?
In matching, you match each of the subjects in your treatment group with a counterpart in the comparison group. The matched subjects have the same values on any potential confounding variables, and only differ in the independent variable. In statistical control, you include potential confounders as variables in your regression.
What is the definition of a comparison group?
Comparison group. The group of students, teachers, or schools that does not participate in the intervention. Variable. Anything that has a quantity or quality that varies and can be measured. Outcome variable. Variable of interest that the intervention is designed to improve, such as teacher evaluation ratings or student test scores.
What should be the purpose of a control group?
What your control group should be is largely a substantive / theoretical question, not a statistical question. That is, your control group should be designed to help you answer the theoretical question that you are conducting your study to answer.