Confounding
Many factors can influence whether or not a subject will develop an outcome of interest. As a simple example, consider a study with the goal of determining whether physical activity reduces the risk of heart disease.
Methods of Assignment
The distinguishing feature of an intervention study is that the investigators assign subjects to a treatment (or "exposure") in order to establish actively treated groups of subjects and a comparison group.
What The Researchers Did
What The Researchers Found
- Treatment #1 yielded a turnout rate 1.8 percentage points higher than the control group's. Previous researchers have tried things similar to treatment #1 and found similar results. Treatment #2 raised turnout 2.5 points relative to the control. Treatment #3 raised it 4.9 relative to the control. These are large changes. But treatment #4 raised turn...
So What Does This All Mean?
- It means two things. First, it means that there is a substantial internal"civic duty" motivation that gets people to vote. Sure, they might vote because they care about the outcome, or because they think their vote matters for the outcome. But (as treatment #1 shows) they also vote because they want the internal "warm fuzzies" of voting. Second, there is an even stronger external"civic duty" …