Average Heights

Data

I downloaded heights data as the CSV file used below from Our World in Data. (Click on Download and then on Full Data (CSV).) It gives heights in centimeters for males and females and for various countries. The page provides the following explanation: “The data shown here is based on a global study, published by NCD Risk Factor Collaboration (NCD-RisC) in 2016. This dataset is based on both demographic and health surveys as well as academic studies. It reports mean height for adults by year of birth, from 1896 to 1996; in other words, people who had reached their eighteenth birthday from 1914 to 2014.”

library(tidyverse)
heights <- read_csv(
  file = "average-height-by-year-of-birth.csv"
) %>%
  rename(Male = `Mean male height (cm)`, Female = `Mean female height (cm)`)

Here’s a little bit of the data:

head(heights)

## # A tibble: 6 x 5
##   Entity      Code   Year  Male Female
##   <chr>       <chr> <dbl> <dbl>  <dbl>
## 1 Afghanistan AFG    1896  161.   149.
## 2 Afghanistan AFG    1897  161.   149.
## 3 Afghanistan AFG    1898  161.   149.
## 4 Afghanistan AFG    1899  161.   150.
## 5 Afghanistan AFG    1900  161.   150.
## 6 Afghanistan AFG    1901  161.   150.

Dutch Females and Indian Males Compared

ggplot(mapping = aes(x = Year)) +
  geom_line(data = subset(heights, Entity == "Netherlands"), mapping = aes(y = Female), color = "red") +
  geom_line(data = subset(heights, Entity == "India"), mapping = aes(y = Male), color = "blue") +
  labs(x = NULL, y = "Height (cm)") 

The heights of adult Dutch females and adult Indian males are in red and blue, respectively. Note that the average Dutch female caught up with the average Indian male in height at around 1925. For 1996, which is the latest year for which this data set provides information, the height of the average Dutch female was 168.72 cm and the height of the average Indian male was 164.95 cm.

Let’s repeat the above exercise with a different graphing style:

ggplot(mapping = aes(x = Year)) +
  geom_line(data = subset(heights, Entity == "Netherlands"), mapping = aes(y = Female, color = "Netherlands Female")) +
  geom_line(data = subset(heights, Entity == "India"), mapping = aes(y = Male, color = "India Male")) +
  labs(x = NULL, y = "Height (cm)") 

R Techniques Used

• readr::read_csv() to import data from a CSV file
• dplyr::rename() to rename variables
• ggplot2package to plot multiple time series with specified colors
• ggplot2 package to plot multiple time series with specified legend

The End