Lay out the design for two betweensubjects experiments a an

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 3, 2, and 2 levels, respectively.

Solution

a)an experiment involving an experimental group and a control group:

a group of rats are given a drug, and another group of rats are given a placebo....

The experimental group are the drug rats, and the control group are the placebo rats.

What the control is meant to do in this experiment is to compensate for whatever effect (if any) making a rat take a pill, or giving the rat an injection might have on the rat. A good control for an experiment would be one where they only difference between the experiment and the control is whatever it is you\'re trying to study/measure. A rat given no drug at all isn\'t as good of a control as the rat given the placebo. Consider the possibility that the actual administration of the placebo (say an injection) actually has some effect on the rat.

b)

Let the three independent variables be x, y , z

X Y Z

3 2 2

=> IV = 3 x 2 x 2

eg: A researcher who wants to examine the effect of style of dress (e.g., formal versus causual verses traditional) and manner of interaction (e.g., 10 questions versus 10 comments about the job) and IQ level (question verses answer) . In this example there are three IVs (style of dress and manner of interaction and IQ level) . Each of the IVs has 3,2,2 levels respectively. Factorial research designs are described by use of an equation. In this example, the study is described as a 3 (dress) X 2 (interaction) X 2(IQ) factorial research design.