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| Wilson | Newcombe (1998) suggests using alternatives to the usual Wald procedure to obtain confidence intervals for a proportion, particularly for proportions less than 0.2 or greater than 0.8. He suggests the exact binomial method and Wilson’s (1927) method provide slightly better coverage. Confidence intervals for both Wald and Wilson methods may be computed by using [attachment:BinomialCIs_wald_rev.xls this spreadsheet]. |
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| Spreadsheet | You can also obtain confidence intervals for the difference in two proportions [http://www.quantitativeskills.com/sisa/statistics/t-test.htm here.] Formulae used for the difference in proportions in 2x2 tables are described [:FAQ/ChiEqual: here]. |
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| [Last updated on 27 November, 2003] | * [:FAQ/BinomialConfidence/2gp:Confidence interval for differences in two independent binomial proportions] |
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| [wiki:FAQ Return to Statistics FAQ page] | __References__ |
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| [wiki:CbuStatistics Return to Statistics main page] | Newcombe RG. (1998) Two sided confidence intervals for the single proportion: Comparison of seven methods. Statistics in Medicine 1998;17:857-872 |
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| [http://www.mrc-cbu.cam.ac.uk/ Return to CBU main page] | Wilson EB (1927) Probable inference, the law of succession, and statistical inference. J Am Stat Assoc 22, 209-212. |
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| These pages are maintained by [mailto:ian.nimmo-smith@mrc-cbu.cam.ac.uk Ian Nimmo-Smith] and [mailto:peter.watson@mrc-cbu.cam.ac.uk Peter Watson] | ---- |
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| Last updated on 12 February, 2008 |
Confidence Interval for Binomial Proportions
Newcombe (1998) suggests using alternatives to the usual Wald procedure to obtain confidence intervals for a proportion, particularly for proportions less than 0.2 or greater than 0.8. He suggests the exact binomial method and Wilson’s (1927) method provide slightly better coverage. Confidence intervals for both Wald and Wilson methods may be computed by using [attachment:BinomialCIs_wald_rev.xls this spreadsheet].
You can also obtain confidence intervals for the difference in two proportions [http://www.quantitativeskills.com/sisa/statistics/t-test.htm here.] Formulae used for the difference in proportions in 2x2 tables are described [:FAQ/ChiEqual: here].
- [:FAQ/BinomialConfidence/2gp:Confidence interval for differences in two independent binomial proportions]
References
Newcombe RG. (1998) Two sided confidence intervals for the single proportion: Comparison of seven methods. Statistics in Medicine 1998;17:857-872
Wilson EB (1927) Probable inference, the law of succession, and statistical inference. J Am Stat Assoc 22, 209-212.
Last updated on 12 February, 2008