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Insomnia and education. Many workers suffer from stress and chronic insomnia. 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 (February 2005). Adults living in Tennessee were selected to participate in the study using a random-digit telephone dialing procedure. In addition to insomnia status (normal sleeper or chronic insomnia), the researchers classified each participant into one of four education categories (college graduate, some college, high school graduate, and high school dropout). One dependent variable of interest to the researchers was a quantitative measure of daytime functioning called the Fatigue Severity Scale (FSS). The data were analyzed as a 2  4 factorial experiment, with Insomnia status and Education level as the two factors.

a. Determine the number of treatments for this study. List them.

b. The researchers reported that “the Insomnia * Education interaction was not statistically significant.” Practically interpret this result. (Illustrate with a graph.)

c. The researchers discovered that the sample mean FSS for people with insomnia was greater than the sample mean FSS for normal sleepers, and this difference was statistically significant. Practically interpret this result.

d. The researchers reported that the main effect of Education was statistically significant. Practically interpret this result.

e. Refer to part d. In a follow-up analysis, the sample mean FSS values for the four Education levels were compared using Tukey’s method (a = .05), with the results shown below. What do you conclude?