https://github.com/chipbell4/chi-squared-test

Node module for calculating a Chi-Squared probability
https://github.com/chipbell4/chi-squared-test

Last synced: 9 days ago
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Node module for calculating a Chi-Squared probability

• Host: GitHub
• URL: https://github.com/chipbell4/chi-squared-test
• Owner: chipbell4
• Created: 2015-01-29T02:10:21.000Z (almost 10 years ago)
• Default Branch: master
• Last Pushed: 2015-03-16T00:40:30.000Z (over 9 years ago)
• Last Synced: 2024-10-28T17:33:10.333Z (19 days ago)
• Language: JavaScript
• Size: 154 KB
• Stars: 3
• Watchers: 3
• Forks: 3
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# Chi-Squared Test

This package provides a small function for calculating a chi-squared test on a given dataset. Given an observed set of

frequencies `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).probability;

// 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).probability;

// Gives back 0.415881, which is indicates that they did come from the same distribution (by most statistical standards)

```