Binned Scatter Plot for RD Analysis — rd

Produces a publication-ready RD plot that clearly visualises the discontinuity at the cutoff by displaying bin means and a polynomial fit on each side, with an optional confidence ribbon.

Usage

rd_binscatter(
  y,
  x,
  cutoff = 0,
  nbins = 20,
  poly_order = 1,
  show_ci = TRUE,
  xlab = "Running Variable",
  ylab = "Outcome",
  title = NULL
)

Arguments

y: Numeric vector. Outcome variable.
x: Numeric vector. Running variable (same length as y).
cutoff: Numeric. The RD cutoff value. Default 0.
nbins: Integer. Number of bins on each side of the cutoff. Default 20.
poly_order: Integer. Degree of the polynomial fit (1 = linear, 2 = quadratic). Default 1.
show_ci: Logical. Show 95% confidence ribbon around the polynomial fit. Default TRUE.
xlab: Character. x-axis label. Default "Running Variable".
ylab: Character. y-axis label. Default "Outcome".
title: Character or NULL. Plot title.

Value

A ggplot2 object.

Details

Binned Scatter Plot for Regression Discontinuity Analysis

Creates a customisable binned scatter plot for regression discontinuity (RD) analysis. The running variable is split into equal-width bins on each side of the cutoff, bin means are computed, and a polynomial of chosen order is fitted separately on each side. Optional 95% confidence bands are shown. The cutoff is marked with a vertical line and a visible gap between the two sides. No dependency on rdrobust is required.

Examples

set.seed(99)
n <- 1000
x <- runif(n, -1, 1)
y <- 1.5 + 0.8 * x + 2.0 * (x >= 0) + rnorm(n, 0, 0.5)

rd_binscatter(
  y         = y,
  x         = x,
  cutoff    = 0,
  nbins     = 20,
  poly_order = 1,
  title     = "RD Binned Scatter: Simulated Data"
)