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

If this item is a DINO item, we have \[ P(00)=P(10)=P(01) \] This is equivalent to say \[ \begin{bmatrix} 1 & -1 & 0 & 0\\ 0 & 1 & -1 & 0\\ \end{bmatrix} \begin{bmatrix} P(00)\\ P(10)\\ P(01)\\ P(11)\\ \end{bmatrix}=\begin{bmatrix} 0\\ 0\\ \end{bmatrix} \] Or, \[ \mathbf{R}\mathbf{P}=\mathbf{0} \]