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Chi-Square Table

The chi-square table provides critical values for the chi-square distribution, which is commonly used in tests of independence, goodness of fit tests, and testing hypotheses about population variance.

How to Use the Chi-Square Table

  1. Locate your degrees of freedom (df) in the leftmost column
  2. Choose the desired significance level (α) from the column headers
  3. The intersection gives you the critical chi-square value
  4. Hover over any value to see the corresponding area in the distribution chart

Important Notes

  • The table shows right-tail critical values
  • For goodness of fit tests: df = number of categories - 1
  • For independence tests: df = (rows - 1) × (columns - 1)
  • The chi-square distribution is always right-skewed, but becomes more symmetric as df increases
  • All chi-square values are non-negative since they're based on squared differences

Examples of Finding Critical Values

Example 1: Goodness of Fit Test

Suppose you are conducting a goodness of fit test with 5 categories (df = 4) and a significance level of α = 0.05.

  1. Find df = 4 in the leftmost column
  2. Look for the column with α = 0.05
  3. The critical value is 9.488
  4. Reject H₀ if your calculated chi-square statistic is greater than 9.488
R
qchisq(1 - 0.05, 4)
# [1] 9.487729

Example 2: Test of Independence

For a chi-square test of independence with a 3×4 contingency table (df = (3-1)×(4-1) = 6) and a significance level of α = 0.01:

  1. Find df = 6 in the leftmost column
  2. Look for the column with α = 0.01
  3. The critical value is 16.812
  4. Reject H₀ if your calculated chi-square statistic is greater than 16.812
R
qchisq(1 - 0.01, 6)
# [1] 16.81189

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