R/data-twins.R

In openintro: Datasets and Supplemental Functions from 'OpenIntro' Textbooks and Labs

#' twins
#'
#' A data frame containing data collected in the mid 20th century by Cyril Burt from a study tracked down identical twins who were separated at birth: one child was raised in the home of their biological parents and the other in a foster home. In an attempt to answer the question of whether intelligence is the result of nature or nurture, both children were given IQ tests.
#'
#' @name twins
#' @docType data
#' @format A data frame with 27 observations on the following 2 variables.
#' \describe{
#'   \item{foster}{IQ score of the twin raised by Foster parents.}
#'   \item{biological}{IQ score of the twin raised by Biological parents.}
#'   }
#' @keywords datasets
#' @examples
#'
#' library(ggplot2)
#' library(dplyr)
#' library(tidyr)
#'
#' plot_data <- twins |>
#'   pivot_longer(cols = c(foster, biological), names_to = "twin", values_to = "iq")
#'
#' ggplot(plot_data, aes(iq, fill = twin)) +
#'   geom_histogram(color = "white", binwidth = 5) +
#'   facet_wrap(~twin) +
#'   theme_minimal() +
#'   labs(
#'     title = "IQ of identical twins",
#'     subtitle = "Separated at birth",
#'     x = "IQ",
#'     y = "Count",
#'     fill = ""
#'   )
#'
"twins"