A statistical test that allows one to determine whether observed quantities of a specific characteristic differed from the expected value purely by chance.

For one-way frequency tables, PROC FREQ performs a chi-square goodness-of-fit test when you specify the CHISQ option. The other chi-square tests and statistics described in this section are defined ...

Sufficient replication within subpopulations is required to make the Pearson and deviance goodness-of-fit tests valid ... is distributed as chi-square when there is no replication in any of the ...

The chi-square value is calculated using the following formula: Using this formula, the difference between the observed and expected frequencies is calculated for each experimental outcome category.