Chapter 7 2114

Chapter 7 2114 - Chapter 7 Statistical Intervals...

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Unformatted text preview: Chapter 7 Statistical Intervals (Confidence Intervals) Based on a Single Sample 1 Application of Confidence Intervals Physicians’ reaction to Patient Size Background: “Currently, almost one in every two Americans is overweight and one in every five is obese. These individuals face discrimination on a daily basis in employment, education, and relationship contexts. They are viewed as having a physical, moral and emotional impairment and there is a tendency for others to hold them responsible for their condition. Physicians -- people who are trained to treat all their patients warmly and have access to literature suggesting uncontrollable and hereditary aspects of obesity -- also believe obese individuals are undisciplined and suffer from controllability issues.” http://www.ruf.rice.edu/~lane/case_studies/weight/index.html A study was conducted by Mikki Hebl and Jingping Xu and looked at physicians' treatment of obesity in their patients. In the study, medical records for patients displaying symptoms of migraine headaches but otherwise healthy were sent to 122 primary care physicians in Texas. The doctors were asked about how they would treat the patients and about their reactions to the patients. The charts were grouped by Body Mass Index (BMI) into three categories of average, overweight, and obese and this information was included in the charts. The data provided here shows the results of the average and overweight conditions for a specific measure…how much time the physician believed they would spend with the patient. The times for the two groups (1 – Average weight individuals and 2 – Overweight individuals) are shown on the next page. The researchers’ noted that “although the distributions of times are not quite normal, they are not so deviant as to make the test invalid.” They are referring to a specific hypothesis test which they applied and we will see in Chapter 9. 2 3 1. Give point estimates for the mean time to be spent with each group. 2. What is the estimated standard error of each of your estimates? 3. Give a 2 standard deviation range for each of the estimates… Group 1 (Average Weight) Group 2 (Overweight) 15 30 20 20 15 20 30 15 45 30 30 15 40 20 20 20 45 30 25 45 20 20 20 15 40 20 20 60 30 30 30 15 40 25 30 15 30 20 15 20 30 40 30 15 50 30 20 30 30 30 5 30 45 30 20 30 45 30 15 30 30 30 30 50 25 30 30 30 30 30 30 n 33 n 38 Sample mean 31.364 Sample mean 24.737 Sample std. dev. 9.864 Sample std. dev. 9.653 Application of Confidence Intervals Making sense of polling data Suppose that in a poll of 1000 likely voters taken recently, 480 voters chose John McCain as their preferred candidate in the Presidential election while 520 voters selected Barack Obama....
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This note was uploaded on 04/17/2011 for the course ENGR 0020 taught by Professor Rajgopal during the Spring '08 term at Pittsburgh.

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Chapter 7 2114 - Chapter 7 Statistical Intervals...

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