# nWilson: Calculate a simple random sample size for estimating a... In PracTools: Tools for Designing and Weighting Survey Samples

 nWilson R Documentation

## Calculate a simple random sample size for estimating a proportion

### Description

Calculate a simple random sample size for estimating a proportion using the Wilson method.

### Usage

``````nWilson(moe.sw, alpha = 0.05, pU, e)
``````

### Arguments

 `moe.sw` switch for setting desired margin of error (1 = CI half-width on the proportion; 2 = CI half-width on a proportion divided by `pU`) `alpha` 1 - (confidence level) `pU` population proportion `e` desired margin of error; either the value of CI half-width or the value of the half-width divided by `pU`

### Details

Calculate a simple random sample size using the Wilson (1927) method. A margin of error can be set as the CI half-width on the proportion (`moe.sw=1`) or as the CI half-width as a proportion of the population value `p_U` (`moe.sw=2`).

### Value

 `n.sam` numeric sample size `"CI lower limit"` lower limit of Wilson confidence interval with computed sample size `"CI upper limit"` upper limit of Wilson confidence interval with computed sample size `"length of CI"` length of Wilson confidence interval with computed sample size

### Author(s)

Richard Valliant, Jill A. Dever, Frauke Kreuter

### References

Valliant, R., Dever, J., Kreuter,F. (2018, chap. 3). Practical Tools for Designing and Weighting Survey Samples, 2nd edition. New York: Springer.

Wilson, E.B. (1927). Probable inference, the law of succession, and statistical inference. Journal of the American Statistical Association, 22, 209-212.

### See Also

`nCont`, `nLogOdds`, `nProp`, `nPropMoe`

### Examples

``````# srs sample size using Wilson method so that half-width of a 95% CI
# is 0.01. Population proportion is 0.04
nWilson(moe.sw = 1, pU = 0.04, e = 0.01)
``````

PracTools documentation built on Nov. 9, 2023, 9:06 a.m.