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Question;1. Peak;expiratory flow (PEF) is a measure of a patient?s ability to expel air from the;lungs. Patients with asthma or other;respiratory conditions often have restricted PEF. The mean PEF for the population of children is;306. An investigator wants to test;whether children with chronic bronchitis have restricted PEF. A sample of 60 children with chronic;bronchitis is studied, and its mean PEF is 279 with a standard deviation of 85. Is there statistical evidence of a lower mean;PEF in children with chronic bronchitis?;Run the appropriate test at?=0.05. If the results of the test are;statistically significant, you must indicate the p-value for the test statistic. This;problem is worth 15 points.;2. Consider;again the study in Problem 1. A different investigator conducts a second study;to investigate whether there is a difference in mean PEF in children with;chronic bronchitis as compared to those without. Data on PEF are collected and summarized in;the following table. Based on the data, is;there statistical evidence of a lower mean PEF in children with chronic;bronchitis (n=25) as compared to;those without chronic bronchitis (n =;25). Run the appropriate test at?=0.05. If the results of the test are;statistically significant, you must indicate the p-value for the test statistic.;This problem is worth 15 points.Note;M= mean, SD = standard deviation.;Chronic Bronchitis;No Chronic;Bronchitis;M;SD;M;SD;PEF;281;68;319;74;3. A;small pilot study is conducted to investigate the effect of a nutritional;supplement on total body weight. Six;participants agree to take the nutritional supplement. To assess its effect on body weight, weights;are measured before starting the supplementation and then after 6 weeks. The data are shown below. Is there a significant increase in body;weight following supplementation? Run;the test at? = 0.05. If the results of the test are statistically significant;you must indicate the p-value for the;test statistic. This;problem is worth 15 points.;Subject;Number;Initial Weight;(lbs);Weight after 6;Weeks;(lbs);1;155;157;2;142;145;3;176;180;4;180;175;5;210;209;6;125;126;4. A;clinical trial is run to investigate the effectiveness of an experimental drug;in reducing preterm delivery to a drug considered standard care and to;placebo. Pregnant women are enrolled and;randomly assigned to receive one of three treatments: the experimental drug;the standard drug, or the placebo. Women;are followed through delivery and classified as either delivering preterm;37 weeks) or not. The data are shown in;the following table.;Experimental Drug;Standard Drug;Placebo;Preterm Delivery;Yes;26;30;36;No;83;74;60;Is there a statistically;significant difference in the proportions of women delivering preterm among the;three treatment groups? Run the test at;? = 0.05. If the results of the test are statistically significant, you must;indicate the p-value for the test;statistic. This;problem is worth 15 points.;5. In;2007, the CDC reported that approximately 6.6 per 1000 (0.66%) children were;affected with autism spectrum disorder.;A sample of 4000 children from Boston is tested, and 280 children from;the sample are diagnosed with autism spectrum disorder. Is the proportion of children affected with;autism spectrum disorder higher in Boston as compared to the national;estimate? Run the appropriate test at?;= 0.05. If the results of the test are statistically significant, you must;indicate the p-value for the test;statistic. This problem is worth 15 points.;Exercise;Group;n;M;SD;Weight Training;20;49.7;10.2;Aerobic Exercise;20;43.1;11.1;Stretching/Yoga;20;57.0;12.5;6. A;clinical trial is run to assess the effects of different forms of regular;exercise on HDL levels in persons between the ages of 18 and 29. Participants in the study are randomly;assigned to one of three exercise groups - Weight training, Aerobic exercise or;Stretching/Yoga ? and instructed to follow the program for 8 weeks. Their HDL levels are measured after 8 weeks;and are summarized below. Note: M=;mean, SD = standard deviation.;Is there a significant difference;in mean HDL levels among the exercise groups?;Run the test at? = 0.05.;HINT: SSerror = 7286.5. This;problem is worth 15 points.;7. A;clinical trial is being planned to investigate the effect of a new experimental;drug designed to reduce total serum cholesterol. Investigators will enroll participants with;total cholesterol levels between 200 and 240, they will be randomized to;receive the new drug or a placebo and followed for 2 months, and the total;cholesterol will be measured.;Investigators plan to run a test of hypothesis at? = 0.05 and want 80%;power to detect a difference of 10 points in mean total cholesterol levels;between groups. They assume that 10% of;the participants randomized will be lost over the 2 month follow-up. How many participants must be enrolled in the;study? Assume that the standard;deviation of total cholesterol is 18.5. This;problem is worth 10 points.

 

Paper#60354 | Written in 18-Jul-2015

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