6.1 Bar plots

• Plot a quantitative variable (e.g. an amount) versus a categorical variable

• Axes showing amounts (e.g. bar charts) start at 0

• Axes labels for the categorical variable are a common frustration. Solutions include:

  • Rotating labels up to 90 degrees

  • Flipping the x and y coordinates

  • Wrapping long labels

• Ordering bars by ascending or descending data values, or by a natural order, aids in perceptability

Since the quantitative variable axis must start at zero, are bar charts suitable for logarithmic scales, ratios, or products (all of which don’t necessarily include zero)?