Researchers at the University of Pennsylvania suggest that a nasal spray derived from pheromones (chemicals emitted by animals when they are trying to attract a mate) may be beneficial in relieving symptoms of premenstrual syndrome (PMS) (Los Angeles Times, January 17, 2003). a. Describe how you might design an experiment using 100 female volunteers who suffer from PMS to determine whether the nasal spray reduces PMS symptoms. b. Does your design from Part (a) include a placebo treatment? Why or why not? c. Does your design from Part (a) involve blinding? Is it single-blind or double-blind? Explain.
Researchers at the University of Pennsylvania suggest that a nasal spray derived from pheromones (chemicals emitted by animals when they are trying to attract a mate) may be beneficial in relieving symptoms of premenstrual syndrome (PMS) (Los Angeles Times, January 17, 2003).
a. Describe how you might design an experiment using 100 female volunteers who suffer from PMS to determine whether the nasal spray reduces PMS symptoms.
b. Does your design from Part (a) include a placebo treatment? Why or why not?
c. Does your design from Part (a) involve blinding? Is it single-blind or double-blind? Explain.
a.
In order to determine whether or not nasal spray reduces PMS symptoms, a researcher is instructed to design an experiment using 100 female volunteers who suffer from PMS.
Answers may vary; one of the possible answers is given below:
Experimental study:
In a designed experimental study, researchers allocate individuals to a certain group under study and change the values of an explanatory variable intentionally, after which, the values of the response variable for each group is recorded.
Randomization:
Randomization minimizes the difference between groups by equally distributing the individuals. By randomizations individuals are assigned to corresponding treatment randomly. Randomization reduces the observer bias, the effect of the order in which the treatments are administered and accounts for the uncontrolled factors in the experiment.
Placebo:
A placebo is a harmless medication, which is used in experiments to define the ‘control group’. A placebo is usually a sugar tablet that looks smells and tastes like the medicine under study in the experiment.
In the experiment, a placebo is the spray given to group B. That is, no spray treatment is placebo.
Give nasal spray to females under group A and give placebo to females under group B.
Conducting experiment:
Step by step procedure to randomly split 100 female volunteers into two groups is given below:
- Assign 01 to 100 numbers to all 100 female volunteers without repetition.
- Use random number generation, to generate 50 numbers from 100 numbers and assign those 50 corresponding females to group A (nasal spray).
- Assign the remaining 50 numbers to group B (placebo).
- After certain period, record the PMS symptoms of women in the both the groups.
- Compare the PMS symptoms of women in group A with the PMS symptoms of women in group B.
Experimental design:
A possible suitable diagram to illustrate the experimental design used by the investigator to test the effectiveness of nasal spray in the reduction of PMS symptoms is given below:
b.
Placebo:
A placebo is a harmless medication, which is used in experiments to define the ‘control group’. A placebo is usually a sugar tablet that looks smells and tastes like the medicine under study in the experiment.
In the experiment, a placebo is the spray given to group B. That is, placebo treatment will appear and smell as nasal spray but it does not contain any ingredient.
If the 50 females do not receive any treatment, then it is difficult for the researcher to study the effectiveness of nasal spray in PMS reduction.
To get accurate results, the individuals who do not receive any treatment should not know that they are not receiving any treatment. The individuals should have an illusion that all subjects are receiving same treatment.
Therefore, to study the effectiveness of nasal spray placebo treatment is used.
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