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ztest()

Usage:
ztest(x[,y],null:val,var:variance,[upper:T or lower:T])



Keywords: probabilities, descriptive statistics, comparisons
ztest() performs a one- or two-sample z-test, depending on whether
one or two variables are given as arguments.  By default there is
a two-tailed alternative, but you may choose one-sided alternatives
by using one of lowertail:T or uppertail:T.

You specify the null value via null:value.  You specify the
variance via var:variance.  For a two-sample test, you may specify
different variances by using a vector of length two.

The output is a vector containing the z-statistic and the p-value.

Because the variance of the data must be known, these tests are
rarely used in practical data analysis.


Gary Oehlert 2006-01-30