Z test for known population standard deviation

Description

Compute the test of hypothesis and compute confidence interval on the mean of a population when the standard deviation of the population is known.

Usage

  z.test(x, mu = 0, sd,
    alternative = c("two.sided", "less", "greater"),
    conf.level = 0.95, ...)

Arguments

Details

Most introductory statistical texts introduce inference by using the Z test and Z based confidence intervals based on knowing the population standard deviation. Most statistical packages do not include functions to do Z tests because the T test is usually more appropriate for real world situations. This function is meant to be used during that short period of learning when the student is learning about inference using Z procedures, but has not learned the T based procedures yet. Once the student has learned about the T distribution the t.test() function should be used instead of this one (but the syntax is very similar, so this function should be an appropriate introductory step to learning t.test()).

Value

An object of class htest containing the results

Note

This function should be used for learning only, real data should generally use t.test().

Author(s)

Greg Snow greg.snow@imail.org with a slight modification (removed the stdev argument) by the package author.

See Also

t.test

Examples

x <- rnorm(25, 100, 5)
z.test(x, 99, 5)