Sample size for a proportion confidence interval

Source: R/statpsych3.R

Computes the sample size required to estimate a population proportion with desired confidence interval precision. Set the proportion planning value to .5 for a conservatively large sample size.

size.ci.prop(alpha, p, w)

Arguments

alpha

alpha level for 1-alpha confidence

p

planning value of proportion

w

desired confidence interval width

Value

Returns the required sample size

Examples

size.ci.prop(.05, .4, .2)
#>  Sample size
#>           93

# Should return:
# Sample size
#          93