A
researcher examined the effect of relaxation training on insomnia.
Subjects received 0, 2, 4, or 8 sessions of relaxation training.
Following training, the researcher measured how long it took the
participants
to fall asleep in their homes. The
average time for each group is presented in the following table:
TRAINING
SESSIONS
MEAN TIME (minutes)
0 72
2 58
4
31
8
14
1.
Provide definitions for independent variable and dependent variable.
2.
Identify the independent and dependent variables in the above scenario.
3.
How many levels of the independent variable are there? Explain.
4.
Is the manipulation a type variable or an amount variable? Explain.
5. Which type of manipulation is being used in this experiment: presence/absence variable, bivalent variable, or multivalent variable? Explain.
6. On a scale of 1 (very low) to 5 (very
high) how would you rate the external validity of this study? Explain.
7.
Given the specifics of the experiment presented above, discuss two possible
confounding variables.