For two samples x and y from normal distributions with unknown means and unknown equal variances, perform a two-sample t-test of the null hypothesis of equal means.
Under the null, the test statistic t follows a Student distribution with df degrees of freedom.
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 alternative mean (x) != mean
(y). If alt is ">", the one-sided alternative
mean (x) > mean (y) is used. Similarly for
"<", the one-sided alternative mean (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.
Package: statistics