Plot HC adjustment factors against leverages

Plots the HC adjustment factors \(g_t\) against the leverage values \(h_t\) stored in a vcov_hc() object. Points with \(h_t > 3p/n\) are highlighted because this threshold is commonly used to flag high-leverage observations in the empirical examples from the HCbeta paper.

Usage

# S3 method for class 'hcinfer_vcov'
plot(x, label_top = 3, ...)

Arguments

x

An object returned by vcov_hc().

label_top

A nonnegative whole number. The observations with the largest adjustment factors are labeled. Use 0 to suppress labels.

...

Unused. Passing named arguments raises an error.

Value

A ggplot2::ggplot() object.

See also

vcov_hc(), hcinfer(), plot.hcinfer()

Examples

schools <- PublicSchools |>
  dplyr::mutate(
    income_scaled = income / 10000,
    income_scaled_sq = income_scaled^2
  )
fit <- lm(expenditure ~ income_scaled + income_scaled_sq, data = schools)

cov <- vcov_hc(fit, type = "hcbeta")
plot(cov)

plot(vcov_hc(fit, type = "hc4"), label_top = 2)