Calculates a point biserial correlation coefficient and the associated p-value.
The point biserial correlation is used to measure the relationship between a binary variable, x, and a continuous variable, y. Like other correlation coefficients, this one varies between -1 and +1 with 0 implying no correlation. Correlations of -1 or +1 imply a determinative relationship.
x : array of bools
y : array of floats
(point-biserial r, :