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Add plot: how new assessment affected recently sold homes w.r.t old

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1 parent b087969 commit 68a5ec28618e5c56f62ea6e3141d14bc93bfad9a @tmoertel committed Feb 27, 2012
Showing with 22 additions and 0 deletions.
  1. +22 −0 analysis.R
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@@ -321,6 +321,7 @@ to_dB <- function(x) 10 * log10(x)
re_comp <- with(re_sales_bldg_effects,
data.frame(PIN = PIN,
Sold_For = SALEPRICE,
+ Was_Assessed_At = Total_Value_2012_Mkt,
Reassessed_At = Total_Value_2013_Reval,
Error_Intensity_dB = to_dB(
Total_Value_2013_Reval / SALEPRICE)))
@@ -349,3 +350,24 @@ qplot(Reassessed_At, Sold_For, data = re_comp,
ggsave(p, file = "out/mtlebo-home-sales-vs-reval.pdf", height = 7, width = 7)
summary(lm(Sold_For ~ Reassessed_At, data = re_comp))
+
+
+
+## For homes that were recently sold, did the reassessment move them
+## closer to their sales prices?
+p <-
+ggplot(re_comp) +
+ geom_segment(aes(x = Reassessed_At, y = Sold_For,
+ xend = Was_Assessed_At, yend = Sold_For), color = "gray") +
+ geom_point(aes(Reassessed_At, Sold_For), color = "blue") +
+ geom_point(aes(Was_Assessed_At, Sold_For), color = "red") +
+ geom_abline(intercept = 0, slope = 8/8, color = "gray") +
+ scale_x_continuous(formatter = "dollar", lim = c(0, 5e5)) +
+ scale_y_continuous(formatter = "dollar", lim = c(0, 5e5)) +
+ xlab("Assessed property value (red = old assessment, blue = new)") +
+ ylab("Recently sold for (2010 or 2011)") +
+ opts(title = "Lebo homes moved closer to sales price under new assessment")
+
+ggsave(p, file = "out/mtlebo-home-sales-vs-reval-and-baseval-movement.pdf",
+ useDingbats = F,
+ height = 7, width = 7)

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