Exploring the KidsFeet dataset in R

Loading libraries and exploring KidsFeet

The KidsFeet dataset comprises of 37 observations from fourth grade students in 1997.

Information collected included birthdate, which foot (Left/Right) is larger, the length and width of the child’s longer foot, sex, and dominant hand (Left/Right).

knitr::opts_chunk$set(message = FALSE)
library(mdsr)
library(RColorBrewer)

glimpse(KidsFeet)

## Rows: 39
## Columns: 8
## $ name       <fct> David, Lars, Zach, Josh, Lang, Scotty, Edward, Caitlin, ...
## $ birthmonth <int> 5, 10, 12, 1, 2, 3, 2, 6, 5, 9, 9, 3, 8, 3, 11, 4, 12, 3...
## $ birthyear  <int> 88, 87, 87, 88, 88, 88, 88, 88, 88, 88, 87, 88, 87, 88, ...
## $ length     <dbl> 24.4, 25.4, 24.5, 25.2, 25.1, 25.7, 26.1, 23.0, 23.6, 22...
## $ width      <dbl> 8.4, 8.8, 9.7, 9.8, 8.9, 9.7, 9.6, 8.8, 9.3, 8.8, 9.8, 8...
## $ sex        <fct> B, B, B, B, B, B, B, G, G, B, B, B, B, B, G, G, G, G, G,...
## $ biggerfoot <fct> L, L, R, L, L, R, L, L, R, R, R, L, L, L, L, R, R, R, L,...
## $ domhand    <fct> R, L, R, R, R, R, R, R, R, L, R, R, R, R, R, R, L, R, L,...

head(KidsFeet, n =5)

##    name birthmonth birthyear length width sex biggerfoot domhand
## 1 David          5        88   24.4   8.4   B          L       R
## 2  Lars         10        87   25.4   8.8   B          L       L
## 3  Zach         12        87   24.5   9.7   B          R       R
## 4  Josh          1        88   25.2   9.8   B          L       R
## 5  Lang          2        88   25.1   8.9   B          L       R

Exploring Kid’s sex and the length of their feet

We will use geom_violin and geom_jitter along with colour blind safe palettes from the RColorBrewer package.

Violin plots are a compact display of a continuous distribution, a blend of geom_boxplot and geom_density.

geom_jitter adds a small amount of random variation to the location of each point, a useful way of handling over-plotting caused by discreteness in smaller datasets.

We find that Boys tend to have larger feet length that girls.

q <- c(0.25, 0.5, 0.75)

KidsFeet %>% ggplot(aes(fill = sex,x = sex, y = length)) + 
        geom_violin(draw_quantiles = q, alpha = 0.6) + 
        scale_fill_brewer(palette = "Paired") +
        geom_jitter(height = 0, width = 0.1)

Exploring Kid’s sex and their dominant hand

We find that majority of the children are right handed, and there are more boys who are left handed than girls.

KidsFeet %>% ggplot(aes(x = sex, fill = domhand)) + geom_bar()