funnel chart

R code of the ggplot2 example

library(ggplot2)
library(dplyr)
library(HistData)

## The placebo-controlled areas of the 1954 polio field trial, from all the
## children of the study grades to those injected with the vaccine.
trial <- filter(PolioTrials, Experiment == "RandomizedControl")
n <- \(groups) sum(trial$Population[trial$Group %in% groups])
stages <- tibble(
  stage = c("Children in the study grades", "Injected at least once",
            "Given all three injections", "Given the vaccine, not the placebo"),
  n = c(n(trial$Group), n(c("Vaccinated", "Placebo", "IncompleteVaccinations")),
        n(c("Vaccinated", "Placebo")), n("Vaccinated"))
) |>
  mutate(y = rev(seq_along(stage)),
         label = paste0(lex_number(n), " (", round(100 * n / n[1]), "%)"))

p <- ggplot(stages) +
  geom_rect(aes(xmin = -n / 2, xmax = n / 2, ymin = y - 0.3, ymax = y + 0.3), fill = "#9b2367") +
  geom_text(aes(x = 0, y = y, label = label), colour = "white", size = 3) +
  geom_text(aes(x = -max(n) / 2, y = y + 0.34, label = stage), hjust = 0, vjust = 0,
            size = 2.8, colour = "#262626") +
  scale_y_continuous(limits = c(0.5, 4.95)) +
  labs(title = "54% of the children in the trial areas had all three injections",
       subtitle = "Placebo-controlled areas of the 1954 polio vaccine field trial",
       x = NULL, y = NULL,
       caption = "Data: Francis et al. 1955, via the HistData R package") +
  theme_lex_viz(grid = "", arrows = "") +
  theme(axis.text = element_blank())