Heating fuel in buildings
Use this diagram to show that bar charts of within-group proportions are easier to compare than bar charts of raw frequencies.
How much has the proportion of buildings using natural gas changed?
The different numbers of buildings in the age groups makes comparisons much harder.
Select Propn within Year of construction. The bar chart for each age group is scaled to have the same total (1.0).
Finally, select Fuel type under the horizontal axis. This clusters the bars by the fuel type and makes it easier to compare the proportions.
In a 1994 report from the US Department of Justice, federal prisoners who had been convicted of drug dealing were classified by race and by the type of drug involved.