used more than 60 million times!

Below you will find descriptions and details for the 5 formulas that are used to compute probability values for the difference between two slopes.

Beta function:

Lower incomplete beta function:

Regularized lower incomplete beta function:

where the numerator is the lower incomplete beta function, and the denominator is the beta function.

t-distribution cumulative distribution function (CDF):

where

t-value for the difference between two slopes:

where

Related Resources