What is the purpose of a comparison group?
In an experiment testing the effects of a treatment, a comparison group refers to a group of units (e.g., persons, classrooms) that receive either no TREATMENT or an alternative treatment. The purpose of a comparison group is to serve as a source of COUNTERFACTUAL causal inference.
When comparison group members become aware that they are being denied some advantage they may increase efforts to compensate creating a problem known as?
When comparison group members are aware that they are being denied some advantage, they may increase their efforts to compensate, creating a problem termed compensa- tory rivalry (Cook & Campbell, 1979).
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.
What is the difference between a control group and a comparison group?
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.
How does a control group increase validity?
Control groups help ensure the internal validity of your research. You might see a difference over time in your dependent variable in your treatment group. However, without a control group, it is difficult to know whether the change has arisen from the treatment.
Does a control group reduce bias?
Having more than one control group increases the power of a study and reduces the bias. Increase in power is achieved because of greater comparability as more information is available regarding potential differences in response between cases and controls.
What are the benefits of having a control group?
The control group consists of elements that present exactly the same characteristics of the experimental group, except for the variable applied to the latter. This group of scientific control enables the experimental study of one variable at a time, and it is an essential part of the scientific method.
Why would a researcher use a quasi-experimental design?
Like a true experiment, a quasi-experimental design aims to establish a cause-and-effect relationship between an independent and dependent variable. Quasi-experimental design is a useful tool in situations where true experiments cannot be used for ethical or practical reasons.
What research design is the strongest and why?
I. A well-designed randomized controlled trial, where feasible, is generally the strongest study design for evaluating an intervention’s effectiveness.