Small n and quasi-experiments review

1. Graph potential results of the following multiple baseline design. A therapist is trying to reduce the problem behaviors of skipping school and fighting in two fifth grade boys.

2. Describe an ABA design to test an intervention for obsessive compulsive disorder.

3. What is the main difference between a quasi-experiment and a true experiment? Between a field experiment and a true experiment?

4. You want to study the effects of 24 hour visitation in the dorms of a college campus on grades. One all-female dorm voted for 24 hour visitation while another did not. You compare the grades of people living in each of these dorms the semester before and the semester after the visitation change. What kind of study have you done? What are some possible threats to internal validity? How could you correct them?

5. I am interested in the effect of a nationwide law allowing female frontal nudity to be shown on network television (pretend it was passed a couple of years ago) on the number of sexual crimes committed in the United States. What type of study might be best?

A. small n design

B. field experiment

C. interrupted time series design

D. nonequivalent control group design

E. longitudinal study

6. The following graph represents the number of suicides per month in city high schools before and after a suicide intervention program that occurred in May 1996. What kind of study is this? Interpret the results. Was the program effective? What are the possible threats to internal validity?

7. A researcher studying developmental changes in intelligence conducted the following cross-sectional study. The Wechsler Adult Intelligence Scale was given to 20 people at each of the following ages: 20, 30, 40, 50, 60, and 70. These are the results:

Age IQ

20 120

30 110

40 100

50 95

60 93

70 89

From these results the researcher concluded that intelligence peaks in the early years and declines steadily thereafter. Do you agree? Why or why not?