5.8 Numeric vs. numeric: Scatterplots + smoother

5.8.1 Data & Packages & functions

• geom_smooth(): Adds smoother
  • geom_smooth(se= FALSE): Display confidence interval around smooth?
• method = "loess"
  • Default for small n, uses a smooth local regression(as described in?loess)
  • Wiggliness of the line is controlled by the span parameter, which ranges from 0 (exceedingly wiggly) to 1 (not so wiggly)
• If n > 1000 alternative smoothing algorithm is used (Wickham 2016, 19)

5.8.2 Graph

• Figure 5.13 and 5.14 provide two examples:
• Questions:
  • What does the graph show? What are the underlying variables (and data)?
  • How many scales/mappings does it use? Could we reduce them?
  • What do you like, what do you dislike about the figure? What is good, what is bad?
  • What kind of information could we add to the graph (if any)?
  • How would you approach a replication of the graph?

Figure 5.13: Small multiples of scatterplots

Figure 5.14: Scatterplot with colored subsets

5.8.3 Lab: Data & Code

# data_twitter_influence.csv
data <- read_csv(sprintf("https://docs.google.com/uc?id=%s&export=download",
                         "1dLSTUJ5KA-BmAdS-CHmmxzqDFm2xVfv6"))
ggplot(data %>% filter(followers_count<50000), 
       aes(x = account_age_years, 
           y = followers_count)) + 
           geom_point(alpha =0.5) + 
           facet_wrap(~party) +
  ylab("Number of followers") +
  xlab("Account age (in years)") +
  scale_x_continuous(breaks = c(0, 5, 10), limits = c(0,10)) +
  geom_smooth(method=lm,  color = "black", fill="lightgray") +
  geom_smooth(span =  0.3) +
  theme_light()

ggplot(data %>% filter(followers_count<50000), 
       aes(x = account_age_years, 
           y = followers_count, 
           color = factor(party))) + 
           geom_point(alpha =0.5) + 
           #facet_wrap(~party) +
  ylab("Number of followers") +
  xlab("Account age (in years)") +
  scale_x_continuous(breaks = c(0, 5, 10), limits = c(0,10)) +
  geom_smooth(method=lm,  aes(fill=party, color=party)) +
  theme_light()

References

Wickham, Hadley. 2016. Ggplot2: Elegant Graphics for Data Analysis. Springer.