Computing the Chi Square Test of Independence (5 of 5)

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Summary of Computations
  1. Create a table of cell frequencies.

  2. Compute row and column totals.

  3. Compute expected cell frequencies using the formula:


    where Eij is the expected frequency for the cell in the ith row and the jth column, Ti is the total number of subjects in the ith row, Tj is the total number of subjects in the jth column, and N is the total number of subjects in the whole table.

  4. Compute Chi Square using the formula:



  5. Compute the degrees of freedom using the formula: df = (R-1)(C-1) where R is the number of rows and C is the number of columns.

  6. Use a chi square table to look up the probability value.


Note that the correction for continuity is not used in the chi square test of independence.


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