Regression Formulas

The following formula are used for linear regression. In case of geometrical regression, x and y have to be substituted by ln x and ln y. In case of exponential regression only y, and in case of logarithmic regression only x has to be substituted.


    a = (Σy - b·Σx)/n
    b = (n·Σxy - Σx·Σy)/(n·Σx2 - Σx·Σx) 

Coeff. of determination  r2 = h1/h2
Coeff. of correlation    r  = √r2

Variance                 s2 = (h2 - h1)/(n-2)
Standard deviation       s  = √s2

with  h1 = b·(Σxy - 1/n·Σx·Σy)  and   h2 = Σy2 - 1/n·Σy·Σy