Fig. 3

Distribution of difference in age at death of the 1989 United States death cohort. To estimate the mean difference and the confidence interval we ran 1,000 bootstraps of subsets of 989 individuals in the dataset to simulate the data from the Halpern and Coren study [1]. The left y-axis indicates the histogram counts, the right y-axis indicates the probability distribution function values (density). The black curve indicates the distribution plot fitted with the KDE method. The long vertical black line indicates the mean difference (9.3 years); the short vertical black lines indicate the confidence interval (4.26–14.40 years)