Case 1: A certain psychologist was looking for the cause of failure among college students. She took a group of former students who had flunked out and a group of students who had received good grades. She gave both groups a self-esteem test and found that the group that flunked out scored lower on the test than did the group that received good grades. She concluded that low self-esteem is one of the causes of college failure and suggested further that a person with low self-esteem probably expects to fail and exhibits defeatist behavior in college, which eventually leads to failure.
What was the independent variable? What was the dependent variable and how is it measured?
Discuss the study's design. What kind of design was used? Was this design appropriate? Why or why not?
Was the experimenter justified in her conclusions? Why or why not?
Case 2: In an effort to determine the effects of the drug chlorpromazine on the performance of schizophrenics, two clinical investigators randomly selected 20 acute schizophrenics from a mental hospital population. The patients were asked to order several stimuli along some dimension, such as ordering eight stimuli by weight. There were several tasks of this sort. All subjects first performed the tasks after being injected with a saline solution (Placebo) and then performed the tasks again several hours later after being injected with chlorpromazine. The results indicated that fewer errors were made in the chlorpromazine treatment, which suggested to the investigators that the drug facilitates more adequate cognitive functioning in this type of patient.
What do you think the hypothesis might be for this study? Is the hypothesis you selected directional or nondirectional? Why did you select a directional or nondirectional hypothesis?
Next, discuss this study's design. What was the design? Was it appropriate? Why or why not?
What was the purpose of random selection in this study?
What is the independent variable? What is the dependent variable and how is it measured?
Are there possible confounds in this study? If so, how would you control for them?
Case 3: Recently, an association that represented police in New Jersey complained that the incidence of cancer was unusually high among police officers who used radar guns in tracking the speed of drivers. The association brought suit against the state, claiming that those officers who used these radar guns had an incidence of cancer 18 percent higher than a comparable group of government workers from the state park service who were randomly selected for comparison purposes. The comparison sample and the police officers were matched on educational level, age, gender, and years of service. The sample was large: 283 police officers and 231 park workers.
Was the case justified? Why or why not? (Be sure to support your answer with reference to the strengths and weaknesses of the design, and consider possible confounds.)
What kind of study is this? What are the problems associated with this kind of study?
How would you improve the study?
Please respond to the posts of at least two of your classmates.