Question

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?

Answer 1

Hypothesis: The drug,chlorpromazine, facilitates an adequate cognitive functioning in patients suffering from Schizophrenia.

The hypothesis mentioned above would be classified under directional (one tailed), as the statement above insinuates the effect of the independent variable onto the dependent variable. And, also, the nature of the effect is elucidated within the hypothesis as well, that is, there is a direction specified in which the experiment would be heading in.

A directional hypothesis is considered for this study as a hypothesis has to be clear as well as precise; as it is the primary predictive and tentative statement that is used to define the purpose of a given study and outline the outcome of the investigation. A directional statement provides the aspects mentioned.  

This would be a classic clinical research design as it involves the testing of a potential pharmaceutical drug, it involves 4 phases, and is quite efficient in drug detailing in all the four stages, starting from the fundamental (preclinical stage) to the Phase IV.

Random selection is necessary as it would make the study more accurate. For example, by selecting a range of patients from the mental hospital population, it reduces the risk of extraneous variables, which the investigator probably might not have taken into consideration that could influence the final results of the studies.

The independent variables would be the drug and the placebo, as they can be changed or controlled by the experimenter to test its affects on the dependent variable. And the dependent variable would be the cognitive functioning of the patients, as it would be the one that changes by the action of the independent variable. In the above context, the changes in the dependent variable would be measured after the application of the independent variable, and then measuring the cognitive functioning of the patients, the level of changes induced, if any, would be the result.

Confounded variable are those variables that aren't included within the cope and the extent of the study, as those are the variables, which the investigator isn't focusing on while studying a certain phenomena. And apart from the independent variable, these variables have an effect on the dependent variable as well. There could be confound variables which could be involved in the study mentioned afore. For example, it is mentioned in the text that after injecting the given drug into the system of patient, there is a gap of several hours interjected before providing them tasks meant to measure their cognitive functioning. There could be numerous variables and possibilities that could occur within that given span of hours which could taint the result of the study or aid in promulgating the affects of the drug. Maybe the drug works better with accompaniment of sleep, the lack of sleep could render useless the affect of the drug.