Chapter 2 Josh Lecture

Chapter 2 Josh Lecture - Chapter 2 Samples, Good and Bad...

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Chapter 2 Samples, Good and Bad
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Motivating Example Suppose that the dean would like to know if all USC students are willing to pay an additional $50 privilege fee to help fund medical technology at USC. 42 out of 50 students in the Thompson Student Health Center waiting room think that the fee is a good idea. Would you advise the Dean to impose the fee?WHY/ Why not?
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Outline How To Sample Badly (Bias) Convenience Sampling Voluntary Response Sampling Simple Random Samples
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How To Sample Badly
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Definition A statistical study is Biased if it systematically favors an outcome. Which outcome is favored in our health example? The study is biased because the sample is bad. The sample is bad because the sample (50 students at Thompson Health Center) is not representative of the population (all Students at USC).
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Motivating Example Suppose that you are hard up for cash. So you buy a crate of 100 apples from Super Store USA and intend to sell them individually for a profit. You squeeze 10 apples from the top of the crate and 9 of them seem to be fresh. You conclude that roughly 90 of the apples in the crate are fresh. Is your conclusion reliable?
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This note was uploaded on 06/13/2011 for the course STAT 110 taught by Professor Johnson during the Spring '07 term at South Carolina.

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Chapter 2 Josh Lecture - Chapter 2 Samples, Good and Bad...

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