Question

Lay out the design for two between-subjects experiments: a) an experiment involving an experimental group and a control group, and b) a factorial design with three independent variables that have three, and two levels respectively.

Answer 1

A. In a between-subjects design, the various experimental treatments are given to different groups of subjects. The subjects are first randomly divided into two groups, an experimental group and a control group. The experimental group is exposed to the manipulation of independent variable whereas the control group only serves as comparison group and receives no exposure to the independent variable manipulation.

B. In this type of a factorial design, each independent variable is a factor in the design. Because there are three factors and each factor has two levels, this is a 2×2×2 factorial design. This design will have 2x2x2=8 different experimental conditions. To conduct this experiment, the investigator would randomly assign individuals to each of the eight experimental conditions. Each experimental condition in this design represents a different treatment protocol.