Figure 6. Model fit between the predicted population unit counts at the Jiedao/Xiangzhen unit compared to the original census counts at the same unit level.
Comparison of validation unit counts divided by unit area (population density) on a log10-log10 scale with those estimated from maps produced using coarser census units. Jiedao/Xiangzhen (Admin. Level 4) were used as validation units and estimated population maps were produced using Quixan (Admin. Level 3) data. The Jiedao/Xiangzhen units represent the finest level census data available for the urban centers of Shanghai, Beijing, Guangdong and Chongqing ((4,274 validation units (1990), 4,274 validation units (2000), 3,265 validation units (2010)). This comparison is an estimate of overall model fit at the Admin. Level 4 level. Contours are plotted at observation density thresholds above which the specified percentage of observations are found. The smoothed fit line showing overall trend is estimated by LOESS (Cleveland, et al. 1992) (ref. 42) (smoothing parameter alpha=0.75).