Is insomnia related to education status? Researchers at the Universities of Memphis, Alabama at Birmingham, and Tennessee investigated this question in the Journal of Abnormal Psychology (Feb. 2005). Adults living in Tennessee were selected to participate in the study, which used a random-digit telephone dialing procedure. Two of the many variables measured for each of the 575 study participants were number of years of education and insomnia status (normal sleeper or chronic insomniac). The researchers discovered that the fewer the years of education, the more likely the person was to have chronic insomnia.

a. Identify the population and sample of interest to the researchers.
b. Identify the data collection method. Are there any potential biases in the method used?
c. Describe the variables measured in the study as quantitative or qualitative.
d. What inference did the researchers make?