as BLUP in the literature (McGilchrist 1993), although this modal predictor
is neither linear nor unbiased in general. The orthodox BLUP of the ran-
dom effects is the linear unbiased predictor of U given Y which minimizes
the mean square distance between the random effects U and their predictor
within the class of linear functions of Y .
Explicit expressions for the mean square distances between the compo-
nents of the random effects U and their predictors are as follows:
c i = E ( U ^ i − U i ) 2 = σ 2 1 + σ 2 ∑ s = 1 a ∑ h = 1 q s ∑ ( i , j , k ) ∈ R ( τ s h ) w i j μ i j k , h ( s ) ,
\begin{align}
c_i &= E(\hat{U}_i - U_i)^2 \\
&= \frac{\sigma^2}{1 + \sigma^2 \sum_{s=1}^{a} \sum_{h=1}^{q_s} \sum_{(i,j,k) \in \mathcal{R}(\tau_{sh})} w_{ij} \mu_{ijk,h}^{(s)}}, \tag{12}
\end{align}
c i = E ( U ^ i − U i ) 2 = 1 + σ 2 ∑ s = 1 a ∑ h = 1 q s ∑ ( i , j , k ) ∈ R ( τ s h ) w ij μ ijk , h ( s ) σ 2 , ( 12 )
where (i, j, k) runs over the risk set $\mathcal{R}(\tau_{sh})$ for fixed i. Here,
μ i j k , h ( s ) = exp ( α s h + β ⊤ x i j k ( s ) ) = exp ( ( α ⊤ , β ⊤ ) x i j k , h ( s ) ) = exp ( γ ⊤ x i j k , h ( s ) ) ,
\begin{align*}
\mu_{ijk,h}^{(s)} &= \exp (\alpha_{sh} + \beta^{\top} \mathbf{x}_{ijk}^{(s)}) \\
&= \exp ((\alpha^{\top}, \beta^{\top}) \mathbf{x}_{ijk,h}^{(s)}) \\
&= \exp (\gamma^{\top} \mathbf{x}_{ijk,h}^{(s)}),
\end{align*}
μ ijk , h ( s ) = exp ( α s h + β ⊤ x ijk ( s ) ) = exp (( α ⊤ , β ⊤ ) x ijk , h ( s ) ) = exp ( γ ⊤ x ijk , h ( s ) ) ,
and, for fixed (i, j),
w i j = ( 1 + ω 2 ∑ s = 1 a ∑ h = 1 q s ∑ ( i , j , k ) ∈ R ( τ s h ) μ i j k , h ( s ) ) − 1 ,
w_{ij} = \left( 1 + \omega^2 \sum_{s=1}^{a} \sum_{h=1}^{q_s} \sum_{(i,j,k) \in \mathcal{R}(\tau_{sh})} \mu_{ijk,h}^{(s)} \right)^{-1},
w ij = 1 + ω 2 s = 1 ∑ a h = 1 ∑ q s ( i , j , k ) ∈ R ( τ s h ) ∑ μ ijk , h ( s ) − 1 ,
where (i, j, k) runs over the risk set $\mathcal{R}(\tau_{sh})$. Similarly, we have
c i j = E ( U ^ i j − U i j ) 2 = w i j { ω 2 + c i w i j } .
\begin{align}
c_{ij} &= E(\hat{U}_{ij} - U_{ij})^2 \\
&= w_{ij} \{ \omega^2 + c_i w_{ij} \}. \tag{13}
\end{align}
c ij = E ( U ^ ij − U ij ) 2 = w ij { ω 2 + c i w ij } . ( 13 )
The cluster random effects predictor can be expressed as
U ^ i = 1 + σ 2 ∑ s = 1 a ∑ h = 1 q s ∑ ( i , j , k ) ∈ R ( τ s h ) w i j Y i j k , h ( s ) 1 + σ 2 ∑ s = 1 a ∑ h = 1 q s ∑ ( i , j , k ) ∈ R ( τ s h ) w i j μ i j k , h ( s ) = c i ( 1 σ 2 + ∑ s = 1 a ∑ h = 1 q s ∑ ( i , j , k ) ∈ R ( τ s h ) w i j Y i j k , h ( s ) ) ,
\begin{align*}
\hat{U}_i &= \frac{1 + \sigma^2 \sum_{s=1}^{a} \sum_{h=1}^{q_s} \sum_{(i,j,k) \in \mathcal{R}(\tau_{sh})} w_{ij} Y_{ijk,h}^{(s)}}{1 + \sigma^2 \sum_{s=1}^{a} \sum_{h=1}^{q_s} \sum_{(i,j,k) \in \mathcal{R}(\tau_{sh})} w_{ij} \mu_{ijk,h}^{(s)}} \\
&= c_i \left( \frac{1}{\sigma^2} + \sum_{s=1}^{a} \sum_{h=1}^{q_s} \sum_{(i,j,k) \in \mathcal{R}(\tau_{sh})} w_{ij} Y_{ijk,h}^{(s)} \right),
\end{align*}
U ^ i = 1 + σ 2 ∑ s = 1 a ∑ h = 1 q s ∑ ( i , j , k ) ∈ R ( τ s h ) w ij μ ijk , h ( s ) 1 + σ 2 ∑ s = 1 a ∑ h = 1 q s ∑ ( i , j , k ) ∈ R ( τ s h ) w ij Y ijk , h ( s ) = c i σ 2 1 + s = 1 ∑ a h = 1 ∑ q s ( i , j , k ) ∈ R ( τ s h ) ∑ w ij Y ijk , h ( s ) ,
where (i, j, k) runs over the risk set $\mathcal{R}(\tau_{sh})$ for any given i. The sub-cluster
random effects predictors are
U ^ i j = w i j U ^ i + ω 2 w i j ∑ s = 1 a ∑ h = 1 q s ∑ ( i , j , k ) ∈ R ( τ s h ) Y i j k , h ( s ) ,
\hat{U}_{ij} = w_{ij}\hat{U}_i + \omega^2 w_{ij} \sum_{s=1}^{a} \sum_{h=1}^{q_s} \sum_{(i,j,k) \in \mathcal{R}(\tau_{sh})} Y_{ijk,h}^{(s)},
U ^ ij = w ij U ^ i + ω 2 w ij s = 1 ∑ a h = 1 ∑ q s ( i , j , k ) ∈ R ( τ s h ) ∑ Y ijk , h ( s ) ,