Mean.CI {LearningStats}

Confidence Interval for the Mean of a Normal Population

Description

Mean.CI provides a pointwise estimation and a confidence interval for the mean of a Normal population in both scenarios: known and unknown population variance.

Usage

Mean.CI(x, sigma = NULL, sc = NULL, s = NULL, n = NULL, conf.level)

Arguments

x

numeric value or vector containing either the sample or the sample mean.

sigma

if known, a single numeric value corresponding with the population standard deviation.

sc

a single numeric value corresponding with the cuasi-standard deviation; not needed if if the sample is provided.

s

a single numeric value corresponding with the sample standard deviation; not needed if the sample is provided.

n

a single positive integer corresponding with the sample size; not needed if the sample is provided.

conf.level

a single value corresponding with the confidence level of the interval; must be a value in (0,1).

Details

The formula interface is applicable when the user provides the sample and also when the user provides the value of the sample characteristics (sample mean, cuasi-standard deviation or sample standard deviation, jointly with the sample size).

Value

A list containing the following components:

estimate

a numeric value corresponding with the sample mean.

CI

a numeric vector of length two containing the lower and upper bounds of the confidence interval.

Independently on the user saving those values, the function provides a summary of the result on the console.

Examples

#Given the sample with known population variance
dat=rnorm(20,mean=2,sd=1)
Mean.CI(dat, sigma=1, conf.level=0.95)

#Given the sample with unknown population variance
dat=rnorm(20,mean=2,sd=1)
Mean.CI(dat, conf.level=0.95)

#Given the sample mean with known population variance:
dat=rnorm(20,mean=2,sd=1)
Mean.CI(mean(dat),sigma=1,n=20,conf.level=0.95)

#Given the sample mean with unknown population variance:
dat=rnorm(20,mean=2,sd=1)
Mean.CI(mean(dat),sc=sd(dat),n=20,conf.level=0.95)