This document discusses the four C's for critiquing a graphic: Content, Construction, Context, and Consumption. It provides an example of critiquing a graphic showing the retreat of Napoleon's army from Moscow in 1812 by analyzing its content about troop locations and numbers, how the graphic is constructed by drawing troops as lines with size and color, the historical context of the retreat, and how the graphic can be consumed or understood by a viewer. The example graphic is polished to improve its appearance.

1. How is a graphic like
pumpkin pie?
The four C’s of critiquing a graphic
Hadley Wickham
Assistant Professor / Dobelman Family Junior Chair
Department of Statistics / Rice University

2. Content

4. Troops: number, location, direction, group
Cities: location, name
Temperatures: location, date, temperature
Rivers?

5. Construction

7. Troops: drawn with a line, position given
by location, size by number of troops,
colour by direction, broken into groups

8. troops <- read.csv("minard-troops.csv")
cities <- read.csv("minard-cities.csv")
ggplot(cities, aes(long, lat)) +
geom_path(aes(size = survivors, colour = direction,
group = interaction(group, direction)), data = troops) +
geom_text(aes(label = city), hjust = 0, vjust = 1, size = 4)
# Polish appearance
last_plot() +
scale_x_continuous("", limits = c(24, 39)) +
scale_y_continuous("") +
scale_colour_manual(values = c("grey50","red")) +
scale_size(to = c(1, 10))

9. Moscou
survivors
55.5 Polotzk Chjat Mojaisk
100,000
Witebsk Tarantino
Gloubokoe Wixma 200,000
55.0 Kowno Malo−Jarosewii
Dorogobouge
Smolensk 300,000
Wilna
54.5 Orscha
Smorgoni Bobr direction
Moiodexno Studienska
A
54.0 R
Minsk Mohilow
24 26 28 30 32 34 36

10. Context

12. Consumption

14. Troops: drawn with a line, position given
by location, size by number of troops,
colour by direction, broken into groups

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