ci.cv: Confidence interval for a coefficient of variation

In statpsych: Statistical Methods for Psychologists

Confidence interval for a coefficient of variation

Description

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.

Usage

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)

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

statpsych documentation built on Sept. 11, 2024, 7:42 p.m.