Ch. 19 part 2

Ch. 19 part 2 - STAT 2053 Elementary Statistics Chapter 19...

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Click to edit Master subtitle style 9/23/11 STAT 2053 – Elementary Statistics Chapter 19 – Inference about a Population Proportion Part 2 11

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9/23/11 Finding the Sample Size The margin of error involves the sample proportion. We’ll have to make a guess on this value when we solve for n . There are two ways to make this guess (call this guess p*): 1. Guess a p* based on pilot studies or past experience with similar studies. 2. Use p* = 0.5. This will maximize the 22
9/23/11 Finding the Sample Size Once we have a guess for the sample proportion, we will get a C% confidence interval for p with a margin of error approximately equal to m when the sample size is: Again, round n up to the nearest whole 33 n = z * m 2 p *(1 - p *)

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Finding the Sample Size Example : Mayor Nathan Bates is running for re-election. We want to estimate what percent of voters intend to vote for him using 95% confidence interval with a margin of error no greater than 3% (0.03). How large a sample do we need? (Guess that the sample proportion is
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This note was uploaded on 09/23/2011 for the course STAT 2053 taught by Professor Staff during the Fall '08 term at Oklahoma State.

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Ch. 19 part 2 - STAT 2053 Elementary Statistics Chapter 19...

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