## Function Students-T-Significance

(

**students-t-significance** < t-statistic > < dof > < tails > )

Student's distribution is much like the Gaussian distribution except with

heavier tails, depending on the number of degrees of freedom, ` dof.' As `

dof'

goes to infinity, Student's distribution approaches the Gaussian. This function

computes the significance of ` t-statistic.' Values range from 0.0 to 1.0: small<br> values suggest that the null hypothesis---that `

t-statistic' is drawn from a t

distribution---should be rejected. The ` t-statistic' parameter should be a<br> float, while `

dof' should be an integer.

The null hypothesis is roughly that ` t-statistic' is zero; you must specify your<br> alternative hypothesis (H1) via the `

tails' parameter, which must be :both,

:positive or :negative. The first corresponds to a two-tailed test: H1 is that

` t-statistic' is not zero, but you are not specifying a direction. If the<br> parameter is :positive, H1 is that `

t-statistic' is positive, and similarly for

:negative.

This implementation follows Numerical Recipes in C, section 6.3.