Confidence Interval Part 1

Confidence Interval Part 1 - ST 260 Margin of Error P41...

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ST 260 Margin of Error P41 1 Department of ISM, University of Alabama, 2006 1 Chapter 7 Confidence Intervals and Sample Size
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ST 260 Margin of Error P41 2 Department of ISM, University of Alabama, 2006 7 General form for “margin of error” when σ is known: m.o.e. = Z c σ n α 2 Z α 2 appropriate percentile from the standard normal distribution, i.e., the Z table. where is the 8 Explanation of symbol: Z ~ N(0,1) α /2 0 Z α /2 Z α /2 cuts off the top tail at area = α /2 .5- α /2
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ST 260 Margin of Error P41 3 Department of ISM, University of Alabama, 2006 9 Amount of confidence Half the Value Table value .95 .90 .80 .98 Z α / 2 Examples 10 11 12 .95 confidence α = .05 risk
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ST 260 Margin of Error P41 4 Department of ISM, University of Alabama, 2006 13 Example 1. Lottery Tickets (Example 7-1 pg. 348) A researcher wishes to estimate the average amount of money a person spends on lottery tickets each month. A sample of 50 people who play the lottery found the mean to be $19 and the standard deviation to be 6.8. Find the best point estimate of the population mean and the 95% confidence interval of the population mean. The best point estimate of the population
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This note was uploaded on 04/20/2008 for the course BER 345 taught by Professor Moore during the Spring '08 term at Alabama.

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Confidence Interval Part 1 - ST 260 Margin of Error P41...

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