Sample size for a confidence interval for any type of parameter

Computes the sample size required to estimate a single population parameter with desired precision using a standard error for the parameter estimate from a prior or pilot study. This function can be used with any type of parameter where the standard error of the parameter estimate is a function of the square root of the sample size (most parameter estimates have this property). This function also assumes that the sampling distribution of the parameter estimate is approximately normal in large samples.

Usage

size.ci.gen(alpha, se, n0, w)

Arguments

alpha

alpha level for hypothesis test

se

standard error of parameter estimate from prior/pilot study

n0

sample size of prior/pilot study

w

desired confidence interval width

Value

Returns the required sample size

Examples

size.ci.gen(.05, 2.89, 30, 8)
#>  Sample size
#>           61

# Should return:
# Sample size
#          61