Perform a signtest of the null hypothesis that x is from a distribution that has a zero median. x must be a vector.

If the second argument m is a scalar, the null hypothesis is that X has median m.

If the second argument y is a vector, the null hypothesis is that the distribution of x - y has zero median.

The argument "alpha" can be used to specify the significance level of the test (the default value is 0.05). The string argument "tail", can be used to select the desired alternative hypotheses. If "tail" is "both" (default) the null is tested against the two-sided alternative median (x) != m. If "tail" is "right" the one-sided alternative median (x) > m is considered. Similarly for "left", the one-sided alternative median (x) < m is considered.

When "method" is "exact" the p-value is computed using an exact method. When "method" is "approximate" a normal approximation is used for the test statistic. When "method" is not defined as an optional input argument, then for length (x) < 100 the "exact" method is computed, otherwise the "approximate" method is used.

The p-value of the test is returned in pval. If h is 0 the null hypothesis is accepted, if it is 1 the null hypothesis is rejected. stats is a structure containing the value of the test statistic (sign) and the value of the z statistic (zval) (only computed when the ’method’ is ’approximate’.

Source Code: signtest