z.test {NCStats} | R Documentation |
Compute the test of hypothesis and compute confidence interval on the mean of a population when the standard deviation of the population is known.
x |
Vector of data values |
mu |
Hypothesized mean of the population |
sd |
Known standard deviation of the population |
alternative |
Direction of the alternative hypothesis |
conf.level |
Confidence level for the interval computation |
... |
Additional arguments are silently ignored |
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
).
An object of class htest
containing the results
This function should be used for learning only, real data should generally use t.test
.
This is z.test
in TeachingDemos but imported and exported here.
z.test(rnorm(25,100,5),99,5)