Visualizing Two Qualitative Variables

Last updated on Jan 27, 2022 R

Bonds

A dataset for illustrating the various available visualizations needs a certain degree of richness with manageable size. The dataset on Bonds contains three categorical and a few quantitative indicators sufficient to show what we might wish.

Loading the Data

Bonds <- read.csv(url("https://raw.githubusercontent.com/robertwwalker/DADMStuff/master/BondFunds.csv"))

A Summary

library(skimr)
Bonds %>%
    skim()
Table 1: Data summary
Name Piped data
Number of rows 184
Number of columns 9
_______________________
Column type frequency:
character 4
numeric 5
________________________
Group variables None

Variable type: character

skim_variable n_missing complete_rate min max empty n_unique whitespace
Fund.Number 0 1 4 6 0 184 0
Type 0 1 20 23 0 2 0
Fees 0 1 2 3 0 2 0
Risk 0 1 7 13 0 3 0

Variable type: numeric

skim_variable n_missing complete_rate mean sd p0 p25 p50 p75 p100 hist
Assets 0 1 910.65 2253.27 12.40 113.72 268.4 621.95 18603.50 ▇▁▁▁▁
Expense.Ratio 0 1 0.71 0.26 0.12 0.53 0.7 0.90 1.94 ▂▇▅▁▁
Return.2009 0 1 7.16 6.09 -8.80 3.48 6.4 10.72 32.00 ▁▇▅▁▁
X3.Year.Return 0 1 4.66 2.52 -13.80 4.05 5.1 6.10 9.40 ▁▁▁▅▇
X5.Year.Return 0 1 3.99 1.49 -7.30 3.60 4.3 4.90 6.80 ▁▁▁▅▇

Most data types are represented. There is no time variable so dates and the visualizations that go with time series are omitted.

Data Visualization

There are three primary visualizations that we might use for a combination of two qualities. We will have a look at geom_tile(), geom_point(), and geom_bar(aes(fill=)) to visualize these. We can also make use of facet. Let me work with Risk and Fees. I will first display the relevant table.

Building a Table

BTDF <- Bonds %>%
    group_by(Risk, Fees) %>%
    summarise(Count = n()) %>%
    data.frame()
## `summarise()` has grouped output by 'Risk'. You can override using the `.groups` argument.
BTDF %>%
    pivot_wider(names_from = Fees, values_from = Count)
## # A tibble: 3 × 3
##   Risk             No   Yes
##   <chr>         <int> <int>
## 1 Above average    37    22
## 2 Average          49    20
## 3 Below average    44    12

The table as a data.frame.

BTDF
##            Risk Fees Count
## 1 Above average   No    37
## 2 Above average  Yes    22
## 3       Average   No    49
## 4       Average  Yes    20
## 5 Below average   No    44
## 6 Below average  Yes    12

geom_tile

BTDF %>%
    ggplot(., aes(x = Risk, y = Fees, fill = Count)) + geom_tile() + scale_fill_viridis_c() +
    theme_minimal() + labs(fill = "Number of Funds")

geom_label a visual table

BTDF %>%
    ggplot(., aes(x = Risk, y = Fees, label = Count)) + geom_label() + theme_minimal() +
    labs(subtitle = "Counts of Funds Shown")

A Tile Table

BTDF %>%
    ggplot(., aes(x = Risk, y = Fees, label = Count, fill = Count)) + geom_tile(alpha = 0.2) +
    scale_fill_viridis_c() + geom_text() + theme_minimal() + labs(subtitle = "Counts of Funds Shown")

Raw Data Plots

geom_count()

Bonds %>%
    ggplot() + aes(x = Risk, y = Fees) + geom_count() + theme_minimal()

geom_bar(fill=)

Now let us look at the bar plot. First, start with Risk.

Bonds %>%
    ggplot() + aes(x = Risk) + geom_bar()

To add Fees to the plot, we can fill the bars.

Bonds %>%
    ggplot() + aes(x = Risk, fill = Fees) + geom_bar()

Conditional Probability: (position="fill")

We can also plot this normalized by the number in each category of x so that the plots represent conditional probability.

Bonds %>%
    ggplot() + aes(x = Risk, fill = Fees) + geom_bar(position = "fill")

plot
Avatar
Robert W. Walker
Associate Professor of Quantitative Methods

My research interests include causal inference, statistical computation and data visualization.

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