If I have one pet peeve about newspapers, it’s how they represent data. So let’s do a pop quiz. Which graph in the image below shows the worse looking trend?
The truth is, they are three representations of the same trend.
Graph A is the most realistic. The Y-axis scale goes from 0 to 480 and the aperture is roughly square.
Graph B distorts the data to look worse than it really is by using a Y-axis scale from 340 to 480. This is a common trick that was used by tobacco companies to show the nicotine levels in their cigarettes versus competitors. Their cigarettes weren’t really much better than the competitors. They just made sure to have the Y-axis cross the X-axis at a point just below their nicotine level, giving the appearance that it was close to nothing.
Graph C has the opposite effect of Graph B. It distorts the data to make the trend look better than it really is. By elongating the X-axis, the downward slope isn’t as steep.
Of course, the Oregonian published one similar to Graph B this morning, showing the last 13 months of factory orders, per U.S. Census Bureau data. Every time I see a graph like that, I think the reading public is getting bamboozled. The data is accurate, but it’s been sensationalized. (And don’t get me started on the one-data-point trends they see in school test scores.)