Nutrition The assessment of diet is an important exposure for many disease outcomes. However, there is often much imprecision in dietary recall. In one study, 70- to 79-yearold women were asked about the preschool diet of their children (ages 2−4) using a food frequency questionnaire (FFQ). A unique aspect of the study is that simultaneous diet record data exist on the same children recorded in real time by their mothers when they were ages 2−4 and their mothers were 20 to 40 years old. The data in Table 11.36 were available on average servings of margarine per week.The Pearson correlation between intake from the two recording methods was 0.448. Assume that FFQ and DR margarine intake are normally distributed. 11.118 Test the hypothesis that the true Pearson correlation (ρ) is significantly different from zero [provide a p-value (two-tailed)]. 11.119 Provide a 95% confidence interval for ρ. The distribution of dietary intake for individual food items is often not very normally distributed.An alternative measure of correlation between the FFQ and DR that does not depend on the assumption of normality is the Spearman rank correlation (rs). For the margarine data, rs = .679.
Nutrition
The assessment of diet is an important exposure for
many disease outcomes. However, there is often much
imprecision in dietary recall. In one study, 70- to 79-yearold women were asked about the preschool diet of their
children (ages 2−4) using a food frequency questionnaire
(FFQ). A unique aspect of the study is that simultaneous
diet record data exist on the same children recorded in
real time by their mothers when they were ages 2−4 and
their mothers were 20 to 40 years old. The data in Table
11.36 were available on average servings of margarine
per week.The Pearson
margarine intake are normally distributed.
11.118 Test the hypothesis that the true Pearson correlation (ρ) is significantly different from zero [provide a p-value
(two-tailed)].
11.119 Provide a 95% confidence interval for ρ.
The distribution of dietary intake for individual food items is
often not very normally distributed.An alternative measure of correlation between the FFQ and DR that does not depend on the assumption of normality is the
11.120 Test the hypothesis that the Spearman rank correlation is significantly different from 0 [provide a p-value
(two-tailed)].
11.121 Provide a 95% confidence interval for the true
Spearman rank correlation (ρs).
![TABLE 11.36 Margarine intake assessed by
two different recording methods
(servings per week, [n = 12])
ID
FFQ
DR
340
7
399
7
0.5
466
502
541
554
7
2.5
558
7
3
605
7
0.5
611
21
3.7
618
2.5
653
21
4.1
707
7
8.5](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F8477f906-f6c4-4c3c-adef-141032124a27%2Fbc468abd-4064-4e7f-ba42-b4e1d8ebc0c5%2Fjz0fc26_processed.png&w=3840&q=75)
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