NONPARAMETRIC STATISTICS

Nonparametric Statistics

Nonparametric Statistics

Before discussing nonparametric techniques, we should consider why the methods we usually use are called parametric. Parameters are indices. For example, there are an infinte number of normal distributions, but each normal distribution is uniquely determined by its mean () and standard deviation (). If you specify all of the parameters (here, and ), you've specified a unique normal distribution.

Most commonly used statistical techniques are properly called parametric because they involve estimating or testing the value(s) of parameter(s)--usually, population means or proportions. It should come as no suprise, then, that nonparametric methods are procedures that work their magic ...