Question

Explain why some studies include both a control group and a placebo treatment. What additional comparisons are possible if both a control group and a placebo group are included?

Short answer

Studies include both a control group and a placebo treatment to control for different sources of bias – the control group for external factors and the placebo group for psychological factors. If both groups are included, apart from comparing the treatment effects with the control and the placebo group, one can also compare the placebo group with the control group to assess the significance of the placebo effect and determine the true therapeutic effect.

Step-by-step solution

Understand the role of the control group and placebo treatment

A control group in a study is used to provide a baseline measure. It's a group that doesn't receive any treatment or intervention and allows researchers to see what would happen without any influence. A placebo treatment, on the other hand, is designed to resemble the actual treatment but doesn't have any therapeutic value. It's used to control for the psychological benefits of treatment.

Explain why studies include both a control group and a placebo treatment

Studies include both a control group and a placebo treatment to address two different sources of bias. The control group helps control for any changes that might happen over time that are not related to the treatment (external factors). The placebo group helps control for the effects of receiving any kind of treatment (psychological factors), as sometimes, people may show improvements simply because they believe they are receiving treatment, known as the placebo effect.

Identify additional comparisons if both control and placebo groups are included

If both a control group and a placebo group are included, apart from comparing the treatment group with each of them separately, one can also compare the placebo group with the control group. This can show whether the placebo effect is significant in this particular study. It can additionally allow for the assessment of the true therapeutic effect, which is the difference between the treatment result and the placebo effect.