Estimated values can be reviewed in a variety of ways including scatter plots, GIS mapping and stratification analysis. Extreme data may create visible problems.
Sample scatter plot-sale ratios versus effective age:
Here the variation in the oldest (+100 years) properties compares reasonably well to the more typical 50 to 60 year ages.
Sample GIS mapping:
Ratios can be mapped to look for patterns and problems. And you can satisfy your inner artist.
Sample stratification statistics:
For an examplehere ratios for the living area size groups are analyzed (estimated sale prices versus time adjusted actual sale prices). The very largest and smallest groups both have medians within one percent of 100. Not surprisingly COD tends to rise at both extremes.