Question

A researcher would like to investigate whether people suffering from insomnia can be helped by taking yoga classes. She designs an experiment as follows. She will obtain a group of volunteer insomniacs who do not currently practice yoga. Each person's degree of insomnia at the start of the experiment will be evaluated.

Volunteers will be randomly assigned to one of three groups. Those in group 1 will practice yoga every day, those in group 2 will practice 3 times per week, and those in group 3 will not practice yoga. At the end of a suitable time period each person's degree of insomnia will again be evaluated. The improvement for the three groups will then be compared. Explain why it is important in this experiment to assign volunteers to groups at random rather than letting them choose their own group.

Answer 1

Volunteers should be assigned to groups at random to eliminate bias and ensure accurate evaluation of the effectiveness of yoga in treating insomnia.

In this experiment, it is important to assign volunteers to groups at random rather than letting them choose their own group. Random assignment ensures that the groups are composed of individuals who are similar in terms of their characteristics, such as age, gender, or previous yoga experience.

This minimizes the potential for confounding variables that could affect the results. If volunteers were allowed to choose their own group, there could be systematic differences between the groups that could impact the validity of the findings.

For example, individuals with a strong interest in yoga might be more likely to choose to practice yoga, leading to biased results. Random assignment helps to eliminate this bias and allows for a more accurate evaluation of the effectiveness of yoga in treating insomnia.