Public school expenditure and income data for US states and Washington DC in 1979. The expenditure value for Wisconsin is missing in the source data, so the standard regression example uses 50 complete observations. The data are useful for illustrating heteroskedasticity-consistent inference because Alaska is a high-leverage observation in the quadratic public-schools model studied in the HCbeta paper.
Format
A tibble with 51 rows and 3 variables:
- state
US state or Washington DC.
- expenditure
Per capita expenditure on public schools in 1979. This variable has one missing value.
- income
Per capita income in 1979.
Source
Greene, W. H. (1993). Econometric Analysis, 2nd ed. Macmillan Publishing
Company, New York. Table 14.1, p. 385. The data were originally sourced from
the U.S. Department of Commerce, Statistical Abstract of the United States
(1979). The dataset is also available in the sandwich R package.
Examples
data(PublicSchools)
PublicSchools[PublicSchools$state == "Alaska", ]
#> # A tibble: 1 × 3
#> state expenditure income
#> <chr> <dbl> <dbl>
#> 1 Alaska 821 10851
schools <- PublicSchools |>
dplyr::mutate(
income_scaled = income / 10000,
income_scaled_sq = income_scaled^2
)
fit <- lm(expenditure ~ income_scaled + income_scaled_sq, data = schools)
hcinfer(fit, type = "hcbeta")
#>
#> ── 🔎 HCbeta robust inference ──────────────────────────────────────────────────
#> 📐 Model: `expenditure ~ income_scaled + income_scaled_sq`
#> Observations: 50 | Parameters: 3
#> 🥪 Robust covariance: HCbeta
#> Confidence level: 95.0% | Normal critical value: 1.9600
#> 💡 Use `summary()` for p-values, test results, confidence intervals, and
#> diagnostics.