This document discusses statistical confidence interval estimation. It covers:
1) Confidence interval estimation for the mean when the population standard deviation is known and unknown.
2) Confidence interval estimation for the proportion.
3) Factors that affect confidence interval width like data variation, sample size, and confidence level.
4) How to estimate sample sizes needed to estimate a population mean or proportion within a given level of precision and confidence.
3. Mean, , is unknown Population Random Sample I am 95% confident that is between 40 & 60. Mean X = 50 Estimation Process Sample
4. Estimate Population Parameter... with Sample Statistic Mean Proportion p p s Variance s 2 Population Parameters Estimated 2 Difference - 1 2 x - x 1 2 X _ _ _
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6. Confidence Interval Sample Statistic Confidence Limit (Lower) Confidence Limit (Upper) A Probability That the Population Parameter Falls Somewhere Within the Interval. Elements of Confidence Interval Estimation
8. 90% Samples 95% Samples Confidence Intervals 99% Samples X _ x _
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10. Confidence Intervals Intervals Extend from (1 - ) % of Intervals Contain . % Do Not. 1 - /2 /2 X _ x _ Intervals & Level of Confidence Sampling Distribution of the Mean to
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12. Mean Unknown Confidence Intervals Proportion Finite Population Known Confidence Interval Estimates
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14. Mean Unknown Confidence Intervals Proportion Finite Population Known Confidence Interval Estimates
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16. Z t 0 t ( df = 5) Standard Normal t ( df = 13) Bell-Shaped Symmetric ‘ Fatter’ Tails Student’s t Distribution
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18. Upper Tail Area df .25 .10 .05 1 1.000 3.078 6.314 2 0.817 1.886 2.920 3 0.765 1.638 2.353 t 0 Assume: n = 3 df = n - 1 = 2 = .10 /2 =.05 2.920 t Values / 2 .05 Student’s t Table
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20. Mean Unknown Confidence Intervals Proportion Finite Population Known Confidence Interval Estimates
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22. Mean Unknown Confidence Intervals Proportion Finite Population Known Confidence Interval Estimates
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