Improving data communication
Lecture 24
November 20, 2023
Bar chart
- Provide the title and axis labels
- Briefly describe the chart and give a summary of any trends it displays
- Convert bar charts to accessible tables or lists
- Avoid describing visual attributes of the bars (e.g., dark blue, gray, yellow) unless there’s an explicit need to do so
Incorporating alt text in Quarto
- Use the
fig-altQuarto chunk option
```{r}
#| fig-alt: "The figure is a bar chart titled 'Total employed Registered Nurses' that
#| displays the numbers of registered nurses in three states (California, New York,
#| and North Carolina) over a 20 year period, with data recorded in three time points
#| (2000, 2010, and 2020). In each state, the numbers of registered nurses increase
#| over time. The following numbers are all approximate. California started off with
#| 200K registered nurses in 2000, 240K in 2010, and 300K in 2020. New York had 150K
#| in 2000, 160K in 2010, and 170K in 2020. Finally North Carolina had 60K in 2000,
#| 90K in 2010, and 100K in 2020."
nurses_subset |>
filter(year %in% c(2000, 2010, 2020)) |>
ggplot(aes(x = state, y = total_employed_rn, fill = factor(year))) +
geom_col(position = "dodge") +
scale_fill_viridis_d(option = "E") +
scale_y_continuous(labels = label_number(scale = 1/1000, suffix = "K")) +
labs(
x = "State", y = "Number of Registered Nurses", fill = "Year",
title = "Total employed Registered Nurses"
) +
theme(
legend.background = element_rect(fill = "white", color = "white"),
legend.position = c(0.85, 0.75)
)
```
Color scales
Use colorblind friendly color scales (e.g., Okabe Ito, viridis)
nurses_subset |>
ggplot(aes(x = year, y = hourly_wage_median, color = state)) +
geom_line(size = 2) +
colorblindr::scale_color_OkabeIto() +
scale_y_continuous(labels = label_dollar()) +
labs(
x = "Year", y = "Median hourly wage", color = "State",
title = "Median hourly wage of Registered Nurses"
) +
theme(
legend.position = c(0.15, 0.75),
legend.background = element_rect(fill = "white", color = "white")
)
The default ggplot2 color scale
Double encoding
Use shape and color where possible
Without direct labeling
With direct labeling
Without whitespace
With whitespace
Accessibility and fonts
library(showtext)
font_add_google(name = "Atkinson Hyperlegible")
nurses_subset |>
ggplot(aes(x = year, y = hourly_wage_median, color = state)) +
geom_line(size = 2) +
colorblindr::scale_color_OkabeIto() +
scale_y_continuous(labels = label_dollar()) +
labs(
x = "Year", y = "Median hourly wage", color = "State",
title = "Median hourly wage of Registered Nurses"
) +
theme_minimal(
base_size = 16,
base_family = "Atkinson Hyperlegible"
)
Enjoy Thanksgiving Break
