Chapter 8, Problem 169P

The EPIC-Norfolk study, a study of diet and cancer in Great Britain, was performed to assess the relationship between dietary intake of vitamin C, plasma levels of vitamin C (in blood), and other predictors. One hypothesis is that smokers might have different vitamin C intake and vitamin C plasma levels than nonsmokers. Dietary intake of vitamin C was obtained using 7-day diet records in which a subject recorded what he or she ate in real time and a computer program was used to estimate nutrient intake based on the diet record data. The data in Table 8.40 were obtained for current smokers and nonsmokers.

Table 8.40 Association between current smoking and diet record intake of vitamin C in the EPIC-Norfolk Study^a

^aDiet record intake includes intake from foods but not from vitamin supplements.

Perform the test in Problem 8.168, and identify whether there is a significant difference between the two variances (i.e., is p < .05 or p > .05?).

8.168 What test can be used to compare the standard deviation of diet record vitamin C intake between current smokers vs. nonsmokers?