Sample size for a mean confidence interval

Computes the sample size required to estimate a population mean with desired confidence interval precision. Set the variance planning value to the largest value within a plausible range for a conservatively large sample size.

size.ci.mean(alpha, var, w)

Arguments

alpha

alpha level for 1-alpha confidence

var

planning value of response variable variance

w

desired confidence interval width

Value

Returns the required sample size

Examples

size.ci.mean(.05, 264.4, 10)
#>  Sample size
#>           43

# Should return:
# Sample size
#          43