% -*- texinfo -*- % @deftypefn {Function File} {[@var{pval}, @var{z}] =} z_test_2 (@var{x}, @var{y}, @var{v_x}, @var{v_y}, @var{alt}) % For two samples @var{x} and @var{y} from normal distributions with % unknown means and known variances @var{v_x} and @var{v_y}, perform a % Z-test of the hypothesis of equal means. Under the null, the test % statistic @var{z} follows a standard normal distribution. % % With the optional argument string @var{alt}, the alternative of % interest can be selected. If @var{alt} is @code{'~='} or % @code{'<>'}, the null is tested against the two-sided alternative % @code{mean (@var{x}) ~= mean (@var{y})}. If alt is @code{'>'}, the % one-sided alternative @code{mean (@var{x}) > mean (@var{y})} is used. % Similarly for @code{'<'}, the one-sided alternative @code{mean % (@var{x}) < mean (@var{y})} is used. The default is the two-sided % case. % % The p-value of the test is returned in @var{pval}. % % If no output argument is given, the p-value of the test is displayed % along with some information. % @end deftypefn

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