8.10 Item-level Relative Fit measures (Cont’d)

The Wald statistic is defined by $$W=[\mathbf{R}\mathbf{P}]^T[\mathbf{R}V(\mathbf{P})\mathbf{R}^T]^{-1}[\mathbf{R}\mathbf{P}]$$ Recall that

$H_0$: the simpler model can fit the item as well as the G-DINA model

$H_1$: the simpler model cannot fit the item as well as the G-DINA model

What if two or more simpler models are retained?