Normal Distribution for Probability-Probability Plots

The Normal distribution function is determined by the following formula:

f(x) = [1/{(2p)1/2 * s}] * e^[-1/2*{(x-m)/s}2]

-∞ < x < ∞



is the mean


is the standard deviation


is the base of the natural logarithm, sometimes called Euler's e (2.71...)


is the constant Pi (3.14...)

Compute from data. When you clear this check box (on the Probability-Probability Plots Advanced tab), you then need to specify both the Mu (m) and Sigma (s) parameters. When you select this check box, STATISTICA estimates Mu (m) and Sigma (s) from the data.

In general, if the observed points follow the Normal distribution with the respective parameters, then they will fall onto the straight line in the P-P plot. Note that you can use the Quantile-Quantile plot to obtain the parameter estimates (for the best fitting distribution from a family of distributions) to enter here.