Researchers wanted to determine if having a television (TV) in the bedroom is associated with obesity. The researchers administered a questionnaire to 377 twelve-year-old adolescents. After analyzing the results, the researchers determined that the body mass index of the adolescents who had a TV in their bedroom was significantly higher than that of the adolescents who did not have a TV in their bedroom. Complete parts (a) through (e). (d) In the report, the researchers stated, "These results remain significant after adjustment for socioeconomic status." What does this mean? A. The researchers made an effort to avoid confounding by accounting for potential lurking variables. B. It means that socioeconomic status is an explanatory variable and that including this variable in the study changes the results of the study. C. It means that socioeconomic status is not an explanatory variable and that including this variable in the study does not change the results of the study. (e) Does a television in the bedroom cause a higher body mass index? Explain. A. Yes, a television in the bedroom causes obesity because the body mass index of the adolescents who had a TV in their bedroom was significantly higher than that of the adolescents who did not have a TV in their bedroom. B. No, a television in the bedroom does not cause obesity because the body mass index of the adolescents who had a TV in their bedroom was significantly higher than that of the adolescents who did not have a TV in their bedroom. C. No, a television in the bedroom and obesity are associated because the body mass index of the adolescents who had a TV in their bedroom was significantly higher than that of the adolescents who did not have a TV in their bedroom.
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This suggests that socioeconomic status did not confound the results, so the best answer is A. The researchers made an effort to avoid confounding by accounting for potential lurking variables. (e) While the study found an association between having a TV in the Show more…
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Researchers Christelle Delmas and associates wanted to determine if having a television (TV) in the bedroom is associated with obesity. The researchers administered a questionnaire to 379 twelve-year-old French adolescents. After analyzing the results, the researchers determined that the body mass index of the adolescents who had a TV in their bedroom was significantly higher than that of the adolescents who did not have a TV in their bedroom. Source: Christelle Delmas, Carine Platat, Brigette Schweitzer, Aline Wagner, Mohamed Oujaa, and Chantal Simon. "Association Between Television in Bedroom and Adiposity Throughout Adolescence," Obesity, $15: 2495-2503,2007$ (a) Why is this an observational study? What type of observational study is this? (b) What is the response variable in the study? What is the explanatory variable? (c) Can you think of any lurking variables that may affect the results of the study? (d) In the report, the researchers stated, "These results remain significant after adjustment for socioeconomic status" What does this mean? (e) Can we conclude that a television in the bedroom causes a higher body mass index? Explain.
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Choose one option for each question: a) Analysis of Variance, b) one sample t-test for one population mean, c) one sample z-test for one population mean, d) Chi-squared Goodness of Fit, e) simple linear Regression 1) A farmer wants to know how much rabbits affect his crop yield. He counts the number of rabbit holes for several of his plots as well as the pounds of lettuce that plot yielded. 2) A suspicious gambler thinks that the six-sided die they have been given is not fair; that is, that the chance of a 1, 2, 3, 4, 5, and 6 are not equal. 3) A farmer suspects that their chickens are lighter than average for the chickens' breed. The breed is supposed to weigh 6 pounds after 10 weeks. The farmer takes a sample of 9 chickens from their brood, the mean of the sample is 6.3 pounds and the SD of the sample is 0.8 pounds. 4) The mean household income in a certain state is $70,000. We think a certain county might be more affluent, so we take a simple random sample of 190 households and find their reported income. The mean of the sample is $74,000, the SD of the sample is $21,000. 5) There are many different types of diets, but do some work better than others? Is low fat better than low carb or is some combination best? Researchers (Gardner et al. 2007) conducted a study involving four popular diets: Atkins (very low carb), Zone (40:30:30 ratio of carbs, protein, fat), LEARN (high carbohydrate, low fat), and Ornish (low fat). They randomly assigned women aged 25-50 with a body mass index (BMI) of 27-40 (overweight and obese) to one of the four diets. The 311 women who volunteered for the program were educated on their assigned diet and were observed periodically as they stayed on the diet for a year. At the end of the year, the researchers calculated the change in BMI (e.g., negative means reduction in BMI) for each woman and compared the results across the four diets.
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The researchers continue their hypothesis test about American teenagers watching television by finding critical value(s) and making a conclusion about the null hypothesis. H0: μ = 18; Ha: μ ≠ 18, which is a two-tailed test. α = 0.10 t0 = -1.935 n = 15 Which is the correct conclusion for this one-mean hypothesis test at the 10% significance level? Use the t-table for the critical value(s): df t0.10 t0.05 t0.025 t0.01 t0.005 13 1.350 1.771 2.160 2.650 3.012 14 1.345 1.761 2.145 2.624 2.997 15 1.341 1.753 2.131 2.602 2.947 16 1.337 1.746 2.120 2.583 2.921 Select the correct answer below: Critical value: t0.05 = 1.761 We should reject H0 because t0 < t0.05 (-1.935 < 1.761). So, at the 10% significance level, the data provide sufficient evidence to conclude that the amount of time that American teenagers watch television per week is different than 18 hours. Critical value: t0.10 = 1.345 We should not reject H0 because t0 < t0.05 (-1.935 < 1.345). So, at the 10% significance level, the data does not provide sufficient evidence to conclude that the amount of time that American teenagers watch television per week is different than 18 hours. Critical values: -t0.05 = -1.753 and t0.05 = 1.753 We should reject H0 because t0 > t0.05 (-1.935 < -1.753). So, at the 5% significance level, the data provide sufficient evidence to conclude that the amount of time that American teenagers watch television per week is different than 18 hours. Critical values: -t0.05 = -1.761 and t0.05 = 1.761 We should reject H0 because t0 < -t0.05 (-1.935 < -1.761). So, at the 10% significance level, the data provide sufficient evidence to conclude that the amount of time that American teenagers watch television per week is different than 18 hours. Critical values: -t0.10 = -1.341 and t0.10 = 1.341 We should not reject H0 because t0 > -t0.05 (-1.341 > -1.761). So, at the 10% significance level, the data does not provide sufficient evidence to conclude that the amount of time that American teenagers watch television per week is different than 18 hours. Critical values: -t0.10 = -1.345 and t0.10 = 1.345 We should not reject H0 because t0 > -t0.05 (-1.345 > -1.761). So, at the 10% significance level, the data does not provide sufficient evidence to conclude that the amount of time that American teenagers watch television per week is different than 18 hours.
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