brain

references:
- ISI, exploration 10.5, p.559

library(tidyverse)

data

df <- read.delim("Facebook.txt", header = TRUE)
str(df)
## 'data.frame':    40 obs. of  2 variables:
##  $ friends: num  0.3 1.09 0.39 1.2 0.8 1.71 2.24 2.4 3.23 3.81 ...
##  $ density: num  -2.14 -1.09 -0.72 -0.53 -0.43 -0.26 -0.34 -1.51 -1.45 -1.48 ...

Scatterplot.

ggplot(df, aes(friends, density)) +
  geom_point(shape = 20, color = "darkred") +
  labs(x = "Friends (hundreds)",
       y = "Brain Density",
       title = "Brain Density vs. Number of FaceBook Friends")