Obtain a 95% CI for the mean difference in diet record vitamin C intake between the two groups?

Nutrition

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.

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Mean vitamin C intake (mg/day) Group sd (mg/day) 92.5 57.0 50.4 26.3 306 Nonsmokers Smokers 17