This
unit will calculate the lower and upper limits of the 95% confidence interval for a proportion, according to two methods described by Robert Newcombe, both derived from a procedure outlined by E. B. Wilson in 1927 (references below). The first method uses the Wilson procedure without a correction for continuity; the second uses the Wilson procedure with a correction for continuity.
For the notation used here, n = the total number of observations and k = the number of those n observations that are of particular interest. Thus, if one observes 23 recoveries among 60 patients,
n = 60, k = 23, and the proportion is
23/60 = 0.3833.
To calculate the lower and upper limits of the confidence interval for a proportion of this sort, enter the values of k and n in the designated places, then click the «Calculate» button.
References:
Newcombe, Robert G. "TwoSided Confidence Intervals for the Single Proportion: Comparison of Seven Methods," Statistics in Medicine, 17, 857872 (1998).
Wilson, E. B. "Probable Inference, the Law of Succession, and Statistical Inference," Journal of the American Statistical Association, 22, 209212 (1927).
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©Richard Lowry 2001
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