Question

Suppose that you are the experimenter of a project running several sections of both the experimental group and control group. The sections will be run on Thursday afternoon and Friday morning. The two rooms you have been assigned vary from each other: one has neutral paint on the walls; the other has bright orange psychedelic paint. How can physical effects be minimized as potential confounding influences in this study?

Answer 1

To reduce the physical effects, it is best to use a predetermined order of placing participants into the rooms such that both groups are exposed to the two rooms equal number of times.