Figure 36:

True poststratified preference for 52 PUMA in Massachusetts is the bottom heatmap, which is the vector X_PUMA. The top heatmap corresponds to the 17 PUMA near Boston that are over/undersampled. The true poststratified preference for PUMA j ∈ {1, … , 52} is defined as $\frac{{\sum }_{k\in S_j}{N}_k{\theta }_k}{{\sum }_{k\in S_j}{N}_k}$, where S_j corresponds to the index set for PUMA j and θ_k is the true preference for poststratification cell k.