Confidence interval for a coefficient of variation

Source: R/statpsych1.R

Computes a confidence interval for a population coefficient of variation (standard deviation divided by mean). This confidence interval is the reciprocal of a confidence interval for a standardized mean (see ci.stdmean). An approximate standard error is recovered from the confidence interval. The coefficient of variation assumes ratio-scale scores.

ci.cv(alpha, m, sd, n)

Arguments

alpha

alpha level for 1-alpha confidence

m

estimated mean

sd

estimated standard deviation

n

sample size

Value

Returns a 1-row matrix. The columns are:

  • Estimate - estimated coefficient of variation

  • SE - recovered standard error

  • LL - lower limit of the confidence interval

  • UL - upper limit of the confidence interval

Examples

ci.cv(.05, 24.5, 3.65, 40)
#>   Estimate         SE        LL        UL
#>  0.1489796 0.01817373 0.1214381 0.1926778

# Should return:
#  Estimate        SE        LL       UL
# 0.1489796 0.01817373 0.1214381 0.1926778