Data set: Cholesterol
Cholesterol is a waxy substance found in blood and cell membranes. All animals need some cholesterol in their system; however, too much cholesterol can cause heart attacks and strokes. A study was conducted to determine how exercise, diet, and three types of drugs impact cholesterol levels. Seventy-two patients at a nearby hospital who had been diagnosed with high cholesterol (a level greater than 240 milligrams per deciliter) consented to be in the study. Each of the 72 patients was randomly assigned to a specific treatment, and after six months the patients’ cholesterol levels were measured again. These measurements are provided in the Cholesterol data set.
a. List two potential nuisance variables for the study. Suggest methods you would use to account for these two nuisance variables.
b. Create appropriate graphs/ charts to check for equal variances and normality. Does it appear that it is appropriate to use ANOVA to analyze these data? Show your work and give concise but appropriate explanations.
c. Make the assumption that ANOVA is appropriate for the data above (i. e., do not transform any data). Using software, conduct an ANOVA for the data that will analyze all main effects, as well as all two- way interactions. Clearly and concisely interpret the results. Create appropriate graphs/ charts that describe the data. Interpret these charts/ graphs. Be selective in which graphs/ charts to supply—too many graphs/charts can detract from your presentation.