Inferential Statistics Definition

Inferential statistics is defined as the branch of statistics that is used to make inferences about the characteristics of a populations based on sample data.

• The goal is to go beyond the data at hand and make inferences about population parameters.

• In order to use inferential statistics, it is assumed that either random selection or random assignment was carried out (i.e., some form of randomization must is assumed).

contributed by Karen Burke, EdD

Parametric versus non-parametric tests

Many statistical tests are based upon the assumption that the data are sampled from a normal distribution. These tests are referred to as parametric tests. Parametric tests are generally used on interval or ratio data.

Tests that do not make assumptions about the population distribution are referred to as nonparametric tests. Non-parametric tests are used when data ranks the outcome variable from low to high (ordinal level data) or if data groups are nominal.

contributed by Frank LaBanca, EdD