A Researcher Would Like to Investigate Whether People Suffering from Insomnia

Essay

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 to assign volunteers to groups at random rather than letting them choose their own group.