This package provides a small function for calculating a chi-squared test on a given dataset. Given an observed set of
observations, an expected set of frequencies
expectations, and the number of degrees of freedom reduced
in the measurement, calculates the probability that the observations came from the same probability distribution.
For example, let's check a die for fairness:
var chiSquaredTest = require('chi-squared-test'); // We expect a fair die var expected = [2, 2, 2, 2, 2, 2]; // Looks pretty unfair... var observed = [6, 3, 3, 0, 0, 0]; // Reduction in degrees of freedom is 1, since knowing 5 categories determines the 6th var reduction = 1; var probability = chiSquaredTest(observed, expected, reduction); // Gives 0.010362, which indicates that it's unlikely the die is fair // However, something a little more likely observed = [1, 2, 4, 4, 2, 1]; probability = chiSquaredTest(observed, expected, reduction); // Gives back 0.415881, which is indicates that they did come from the same distribution (by most statistical standards)