Question

question 39
what is the purpose of a control group?
to manipulate the dependent variable
to manipulate the independent variable
to prevent placebo bias
to serve as a baseline comparison for the manipulation of an independent variable

Explanation:

In an experiment, a control group is left unchanged to provide a standard for comparison. It helps to assess the effect of the manipulation of the independent variable on the dependent variable. It is not about manipulating variables directly and while it can help with placebo - related issues, its main purpose is for comparison.

Answer:

to serve as a baseline comparison for the manipulation of an independent variable