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Fix vignettes/example-ratio-study.Rmd #22

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Merged
wrridgeway merged 3 commits into from
Feb 5, 2026
Merged

Fix vignettes/example-ratio-study.Rmd #22

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b47f39d
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wrridgeway Feb 5, 2026
69ae668
Make sure pins and years are formatted correctly for join
wrridgeway Feb 5, 2026
c149e17
Linting
wrridgeway Feb 5, 2026
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25 changes: 15 additions & 10 deletions vignettes/example-ratio-study.Rmd
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Original file line number Diff line number Diff line change
Expand Up @@ -64,25 +64,30 @@ library(dplyr)
library(jsonlite)
library(stringr)

# Load 100k rows of 2020 residential (major class 2) assessment data
# Load 100k rows of 2022 residential (major class 2) assessment data
assessments <- read_json(
paste0(
"https://datacatalog.cookcountyil.gov/resource/uzyt-m557.json?",
"$where=starts_with(class,'2')&tax_year=2020&$limit=100000"
"$where=starts_with(class,'2')&tax_year=2022&$limit=100000"
),
simplifyVector = TRUE
)
) %>%
# read_json removes leading zeroes, add them back
mutate(pin = str_pad(pin, 14, "left", "0"))

# Load 100k rows of 2020 sales data
# Load 100k rows of 2022 sales data
sales <- read_json(
paste0(
URLencode(paste0(
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@wrridgeway wrridgeway Feb 5, 2026

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Unfortunately I had to use URLencode() here since sending a > sign really pisses off the socrata API.

"https://datacatalog.cookcountyil.gov/resource/wvhk-k5uv.json?",
"year=2020&$limit=100000"
),
"year=2022 and sale_price>=10000&$limit=100000"
)),
simplifyVector = TRUE
) %>%
# read_json removes leading zeroes, add them back
mutate(pin = str_pad(pin, 14, "left", "0"))
mutate(
pin = str_pad(pin, 14, "left", "0"),
year = as.character(as.integer(year))
)
```

### CSV or Excel
Expand Down Expand Up @@ -252,7 +257,7 @@ ggplot(graph_data) +
scale_y_continuous(labels = function(x) paste0(x * 100, "%")) +
labs(
title = "Median Sale Ratios: Open Data Sample",
subtitle = "By decile of sale price in 2020",
subtitle = "By decile of sale price in 2022",
x = "Price Decile Range",
y = "Sale Ratio"
) +
Expand Down Expand Up @@ -357,7 +362,7 @@ MKI <- round(gini_assessed / gini_sale, 4)
KI <- round(gini_assessed - gini_sale, 4)
```

The output for the Modified Kakwani Index is `r MKI`, and the Kakwani Index is `r KI`. According to the following table, this means that the assessments are slightly regressive.
The output for the Modified Kakwani Index is `r MKI`, and the Kakwani Index is `r KI`. According to the following table, this means that the assessments are slightly regressive.

| KI Range | MKI Range | Interpretation |
|:-------------------|:-------------------|:-------------------|
Expand Down