February 2, 2010
Problems with Line Charts Over Time
In this example, the author has one line for Republicans and one line for Democrats. Each line has a point for each year. We all know that only one party can hold the presidency. The author should NOT plot a point for the years in which a party is not in power.
The author presents the data properly (though with a slightly different take on the data itself) with this bar chart, though the vertical axis does not include the entire range of values: