Experiments

A researcher conducts an experiment by applying some treatment to part of a population and then responses are observed and recorded. 

For example, a researcher gives people walking into a movie theater a gift card with $10 on it. Then the researcher observes how many of those people use their gift card to buy concessions. The treatment in this example is the $10 gift card. The researcher wants to know what affect it will have on movie go-ers.

Sometimes, to better observe a population a researcher will divide them into a control group and a treatment group (sometimes also called the experimental group). The control group in the experiment has no treatment applied to it while the people in the treatment group do receive the treatment. In many cases, subjects in the control group may even be given a placebo. A placebo is a harmless, unmedicated, neutral treatment that is made to look like the real treatment. The responses of the control group and the treatment group can then be compared and studied. 

For example, an experiment was conducted in which diabetes patients took cinnamon extract each day while a control group took none. After 40 days, the diabetes patients who took the cinnamon extract each day had reduced their risk of heart disease while the control group had experienced no change. By conducting the experiment in this way it was possible to conclude that taking cinnamon extract had a positive effect in reducing heart disease in diabetes patients.