Testing Differences between p and π (2 of 4)

next previous
The formula for chi square is:

where χ² is the symbol for the chi square, E is an expected cell frequency, and O is an observed cell frequency. The Σ symbol is summation notation and means to sum up the quantity over both cells. Therefore, the formula says that for each cell you

  1. take the absolute value of the difference between the expected cell frequency and the observed cell frequency

  2. subtract 0.5 (the correction for continuity)

  3. square the result,

  4. divide by the expected frequency,

  5. and finally, sum up the values across the cells.

For the present data,

next previous