Box plots for outliers
In addition to indicating the center and spread of a distribution, a box plot
provides a graphical means to detect outliers. You can apply this method to the
msrp column (manufacturer's suggested retail price) to detect if there are unusually
expensive or cheap cars.
This exercise is part of the course
Exploratory Data Analysis in R
Exercise instructions
- Construct a box plot of
msrp. - Exclude the largest 3-5 outliers by filtering the rows to retain cars less than $100,000. Save this reduced dataset as
cars_no_out. - Construct a similar box plot of
msrpusing this reduced dataset. Compare the two plots.
Hands-on interactive exercise
Have a go at this exercise by completing this sample code.
# Construct box plot of msrp
cars %>%
ggplot(aes(x = 1, y = ___)) +
geom_boxplot()
# Exclude outliers from data
cars_no_out <- cars %>%
filter(___)
# Construct box plot of msrp using the reduced dataset
cars_no_out %>%
___ +
___