Consider the diagram shown below.
Assume that 50 people were assigned to each group. Which of the following would
result in the best improvement to this design?
A) Increase sample size to 200 per group
B) Use random assignment to place individuals in each group
C) Decrease the time lag between pretest and post-test
D) Restrict the group composition to include individuals of only one gender
The following two statements refer to experimental causality.
I. In order for causality to be accepted in an experiment, changes in the independent
variable must precede changes in the dependent variable.
II. In order for causality to be accepted in an experiment, only one
alternative explanation of the outcome must be eliminated.
Which, if any, of these statements is (are) true?
A) I only
B) II only
C) I and II are both true