For two samples x and y from normal distributions with unknown means and known variances v_x and v_y, perform a Z-test of the hypothesis of equal means. Under the null, the test statistic z follows a standard normal distribution.
With the optional argument string alt, the alternative of interest can be selected. If alt is
"!="
or"<>"
, the null is tested against the two-sided alternativemean (
x) != mean (
y)
. If alt is">"
, the one-sided alternativemean (
x) > mean (
y)
is used. Similarly for"<"
, the one-sided alternativemean (
x) < mean (
y)
is used. The default is the two-sided case.The p-value of the test is returned in pval.
If no output argument is given, the p-value of the test is displayed along with some information.