91Ó°ÊÓ

A pharmaceutical company developed a new medicine for compulsive behavior. To test this medicine on humans, the company advertised for volunteers who were suffering from this disease and wanted to participate in the study. As a result, 1820 persons responded. Using their own judgment, the group of physicians who were conducting this study assigned 910 of these patients to the treatment group and the remaining 910 to the control group. The patients in the treatment group were administered the actual medicine, and the patients in the control group were given a placebo. Six months later the conditions of the patients in the two groups were examined and compared. Based on this comparison, the physicians concluded that this medicine improves the condition of patients suffering from compulsive behavior. a. Comment on this study and its conclusion. b. Is this an observational study or a designed experiment? Explain. c. Is this a double-blind study? Explain.

Step by step solution

01

Assess the Study and Its Conclusion

This study is an experiment because the patients were assigned a certain treatment, unlike an observational study where no treatments are assigned. The conclusion that the medicine improves conditions depends on how patients were chosen for the treatment and control groups. If the selection was not random rather based on physicians' judgement, there could be a bias that could affect the conclusion.

02

Classify the Type of the Study

This is a designed experiment because treatments were expressly assigned to the participants. In designed experiments, researchers actively control and manipulate the conditions, including treatment allocation. In this case, half the patients were assigned the actual medicine, and the other half were given a placebo.

03

Determine If the Study is Double-Blind

The information given does not specify whether the patients and physicians knew who was receiving the actual medicine and who was receiving the placebo. Thus, it is uncertain whether the study is double-blind or not. A double-blind study ensures that neither the subjects nor the researchers know who belongs to the control or experimental group. This strategy diminishes the risk that expectations or bias could affect the results.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Designed Experiment

When conducting a designed experiment, researchers actively intervene by assigning treatments. In this setup, they manipulate variables to study their effects on subjects, providing a clearer understanding of causation.
In the given study, the researchers assigned an actual medicine to the treatment group and a placebo to the control group. This goes beyond mere observation, aiming to understand the specific impact of the medicine on compulsive behavior.
Designed experiments are crucial in medicine and other fields because they help establish cause-and-effect relationships.

• The control group provides a baseline for comparison, helping to evaluate the true effect of the treatment.
• The treatment group receives the experimental intervention, revealing its potential benefits or harms.

A carefully designed experiment allows researchers to control confounding factors, ensuring that observed changes are due to the treatment itself.

Placebo

A placebo is a crucial component in experimental designs, especially in clinical trials. It is a harmless, inactive substance given to the control group. This helps determine the true effect of the treatment being studied.
In the exercise, the control group received a placebo, mimicking the process of medication without providing the active ingredients. This ensures that any changes in the participants' condition are not just due to psychological effects.
The placebo effect occurs when patients experience real changes in their condition after receiving a placebo. Understanding this effect is important as it can reveal improvements that are not attributable to the treatment itself. By using a placebo, researchers can better isolate the effects of the active medication.
Utilizing placebos helps identify genuine treatment benefits over any psychological or physical changes induced by expectations.

Random Assignment

Random assignment is a key principle in experimental design, ensuring that each participant has an equal chance of being placed in either the treatment or control group.
This process minimizes selection bias by distributing characteristics evenly between groups. In the given study, the physicians used their judgment instead of random assignment, which could introduce bias.
Proper random assignment eliminates pre-existing differences between groups, which can affect the study's outcomes.

• Random assignment enhances internal validity by controlling for variables that researchers may not even be aware of.
• It helps ensure that differences in outcomes are due to the treatment and not pre-existing disparities between groups.

Truly random assignment is essential for credible study results, allowing for more reliable conclusions about the treatment's effectiveness.

Bias in Experimental Studies

Bias is a deviation from truth in the results or inferences of a study. Various types can infiltrate an experimental study, potentially skewing results.
In this experiment, physicians assigned patients using their judgment, introducing allocation bias. This process can lead to unintentional grouping based on unconscious criteria.
Understanding and mitigating bias is crucial in experimental design. It can arise from several sources:

• Selection Bias: Occurs when the study population isn’t representative of the general population.
• Observer Bias: Happens if researchers know which patients received the treatment, potentially altering their assessments.
• Response Bias: Participants may alter responses or behavior simply because they're being studied.

Addressing bias in the design phase by implementing strategies like random assignment, blinding, and standardization of procedures is vital for obtaining more accurate and credible results.