Bulletin – September 2018 Equation (A8)

Ω = [\begin{matrix} σ_{y}^{2} & 0 & 0 & σ_{y} σ_{c} ρ \\ 0 & σ_{u}^{2} & 0 & 0 \\ 0 & 0 & σ_{p}^{2} & 0 \\ σ_{y} σ_{c} ρ & 0 & 0 & σ_{c}^{2} \end{matrix}]