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Chapter 21-Sample proportions A

# Chapter 21-Sample proportions A - Chapter 21 Part A...

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Chapter 21. Part A Confidence Intervals

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Motivation Study – In a random sample of 8474 people with high blood pressure, 633 people were classified as “ severely angry”, 4731 people were “moderately angry”, and 3110 people classified as “not angry”. Medical records over a 20 year period were examined for each individual and whether or not an individual got heart disease was determined. With 95% confidence, angry people were between 1.36 and 3.55 times more likely to get heart disease than non angry people in their lifetime. – Circulation
Motivation Sample data 53/3110 = 1.7% of individuals in the non angry group got heart disease. 27/633 = 4.3% of individuals in the angry group got heart disease. (4.3%)/(1.7%) = 2.5 Why did the article say “With 95% confidence, angry people were between 1.36 and 3.55 times more likely to get heart disease than non angry people in their lifetime.” Circulation

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Outline Estimating Estimating With Confidence Sampling Distribution Formula for a 95% confidence interval.
Estimating

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Definition A parameter is a number that describes a population A statistic is a number calculated on a sample from the population. A statistic is used to estimate a parameter.
Example National Aids Behavioral Survey – What are risk factors for HIV? 170 out of 2673 randomly selected people said they had more than one sexual partner in the past year. What is a statistic that we could use to estimate the proportion of people who had more than one sexual partner? What is the population parameter?

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Inference Inference is the process of using a sample from a population to make a claim about the entire population Use sample statistic
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