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