R/helper_plot_correlation.R

In konfound: Quantify the Robustness of Causal Inferences

# plot correlation

plot_correlation <- function(r_con, obs_r, critical_r) {
  d <- data.frame(x = c(0), y = c(0))

  if (abs(obs_r) > abs(critical_r)) {
    the_title <- "To invalidate an inference"
  } else if (abs(obs_r) < abs(critical_r)) {
    the_title <- "To sustain an inference"
  } else {
    the_title <- "Inference and critical r are exactly equal"
  }

  p <- ggplot2::ggplot(d, ggplot2::aes_string(x = "x", y = "y")) +

    # main arrows
    ggplot2::geom_segment(ggplot2::aes(y = .1), xend = 0, yend = .9, arrow = ggplot2::arrow(), size = 2.5, color = "#A6CEE3") + # straight up
    ggplot2::geom_segment(ggplot2::aes(x = .1), xend = 1, yend = .9, arrow = ggplot2::arrow(), size = 2.5, color = "#A6CEE3") + # hypotenuse
    ggplot2::geom_segment(ggplot2::aes(x = .15, y = 1), xend = .9, yend = 1, arrow = ggplot2::arrow(), size = 2.5, color = "#A6CEE3") + # straight across

    # lagel annotations
    ggplot2::annotate("text", x = 0, y = 0, label = paste0("Confounding\nVariable"), fontface = 3) +
    ggplot2::annotate("text", x = 0, y = 1, label = paste0("Predictor of Interest"), fontface = 3) +
    ggplot2::annotate("text", x = 1, y = 1, label = paste0("Outcome"), fontface = 3) +

    # CV arrows
    # ggplot2::geom_segment(ggplot2::aes(x = .05, y = .25), xend = .275, yend = .65, arrow = ggplot2::arrow(), size = 2.5, color = "#1F78B4") + # straight across
    # ggplot2::geom_segment(ggplot2::aes(x = .175, y = .15), xend = .3, yend = .625, arrow = ggplot2::arrow(), size = 2.5, color = "#1F78B4") + # straight across
    ggplot2::geom_curve(ggplot2::aes(x = .04, y = .325, xend = .35, yend = .825), curvature = -.35, size = 2.5, color = "#1F78B4", arrow = ggplot2::arrow()) +
    ggplot2::geom_curve(ggplot2::aes(x = .225, y = .23, xend = .4, yend = .8), curvature = .35, size = 2.5, color = "#1F78B4", arrow = ggplot2::arrow()) +

    ggplot2::geom_segment(ggplot2::aes(x = .37, y = .81), xend = .465, yend = .925, arrow = ggplot2::arrow(), size = 2.5, color = "#1F78B4") + # straight across

    # corr. annotations
    ggplot2::annotate("text", x = -.125, y = .5, label = paste0("Rx.cv | Z =\n ", r_con), fontface = 1) +
    ggplot2::annotate("text", x = .575, y = .35, label = paste0("Ry.cv | Z =\n", r_con), fontface = 1) +
    ggplot2::annotate("text", x = .25, y = .525, label = paste0("Rx.cv | Z * Ry.cv | Z =\n", round(r_con^2, 3)), fontface = 1) +

    # plot modifications
    ggplot2::xlim(-.15, 1.1) +
    ggplot2::ylim(-.05, 1) +
    ggplot2::theme_void() +
    ggplot2::ggtitle(the_title)

  p
}