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Cigarette smoking has important health consequences and is positively associated with heart and lung diseases. Less well known are the consequences of quitting smoking. A group of 10 nurses, from the Nurses’ Health Study, ages 50−54 years, had smoked at least 1 pack per day and quit for at least 6 years. The nurses reported their weight before and 6 years after quitting smoking. A commonly used measure of obesity that takes height and weight into account is BMI = wt/ht2 (in units of kg/m2). The BMI of the 10 women before and 6 years after quitting smoking are given in the last 2 columns of Table 8.32.
Table 8.32 BMI change in 50- to 54-year-old women over a 6-year period
Suppose the true mean increase in BMI among heavy-smoking women 6 years after quitting is 3.0 kg/m2 with a standard deviation of 2.5 kg/m2. The comparable true mean increase in BMI among never-smoking women over 6 years is 1.5 kg/m2 with a standard deviation of 2.0 kg/m2. How much power does the study in Problem 8.132 have of finding a significant difference if a two-sided test is used with a 5% significance level?
8.132 Implement the test in Problem 8.131, and report a two-tailed p-value.
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Fundamentals of Biostatistics
- A group of 10-year-old boys were first ascertained in a camp for diabetic boys. They had their weight measured at baseline and again when they returned to camp 1 year later. Each time, a serum sample was obtained from which a determination of hemoglobin A1c (HgbA1c) was made. HgbA1c (also called glycosylated hemoglobin) is routinely used to monitor compliance with taking insulin injections. Usually, the poorer the compliance, the higher the HgbA1c level will be. The hypothesis is that the level HgbA1c is related to weight. The data in Table 11.28 were obtained.11.92 What test can be performed to assess the relationship between weight and HgbA1c at the initial visit?11.93 Please perform the test in Problem 11.92, and report a two-tailed p-value.11.94 Do the results in Problem 11.93 imply a relationship between change in HgbA1c and change in weight for an individual boy? Why or why not?11.95 Compute a rank correlation between change in weight and change in HgbA1c, each over 1 year. Use…arrow_forwardA group of 10-year-old boys were first ascertained in a camp for diabetic boys. They had their weight measured at baseline and again when they returned to camp 1 year later. Each time, a serum sample was obtained from which a determination of hemoglobin A1c (HgbA1c) was made. HgbA1c (also called glycosylated hemoglobin) is routinely used to monitor compliance with taking insulin injections. Usually, the poorer the compliance, the higher the HgbA1c level will be. The hypothesis is that the level HgbA1c is related to weight. The data in Table 11.28 were obtained.11.94 Do the results in Problem 11.93 imply a relationship between change in HgbA1c and change in weight for an individual boy? Why or why not?11.95 Compute a rank correlation between change in weight and change in HgbA1c, each over 1 year. Use this measure to directly test the hypothesis that change in weight over 1 year is related to change in HgbA1c. Report a two-tailed p-value, and provide a 95% confidence interval for the…arrow_forwardIf a newborn lab rat receives a hormone and its weight (in ounces) is converted into a z score that is greater than +2.00, what would the researcher most likely conclude about whether or not the hormone had an effect on the rat's weight?arrow_forward
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