Parametric statistics refers to statistics and statistical methods that deal with data with a known probability distribution or that has a distribution's parameters specified. Parametric tests include assumptions about the parameters of data tested, but if a distribution is known e.g. normal, then parameters can be assumed by definition. Parametric tests are almost always more statistically powerful than nonparametric tests given the same amount of data. Examples of parametric tests are the T-tests and ANOVA.