Chi-Square Tests
When using maximum likelihood methods to compare nested models, a chi-square difference test can be used to statistically test the improvement of the more complex model over the simpler nested model. Define View the MathML source as the lack of fit computed using Equation 4.5 when applied to the complex model that has k C parameters, and define View the MathML source as the lack of fit computed using Equation 4.5 when applied to the simpler model that has kS