Lots of reformers “know” that teacher unions are the obstacle to fixing our educational woes. Facts please? Here’s a picture of the relation between teacher union strength in a state and educational outcomes as measured by 8th grade math test scores on the 2011 National Assessment of Educational Progress.
Now the truth about this picture is it’s really a little bit of a tease; it’s a little lead to some recommended reading; and lastly it makes a quite serious point.
Tease: The picture above shows visually that union strength improves education. The result is even (weakly) statistically significant. Part of the tease is that the measures of union strength are from a new report from the Fordham Institute…the Fordham Institute not being a notoriously pro-union group.
Reading recommendation: If you’re interested in teacher unions for sure read the full Fordham report, “HOW STRONG ARE U.S. TEACHER UNIONS? A STATE-BY-STATE COMPARISON.” Much work went into putting together the data. I’ve used their overall ranking of union strength, but authors Winkler, Scull, and Zeehandler provide much more detailed breakdowns.
Serious point: Despite the appearance of the graph above, you can’t seriously conclude from this data that unions improve education. There are just too many other factors not controlled for. (The Fordham report makes this point in greater depth.) But most of today’s political rhetoric slopes the other way. The au courant thinking seems to be that unions are harmful. While you shouldn’t take the apparent upward slope of the data seriously, you surely don’t get a downward slope. In other words, the new data at least suggests not much net educational effect of strong unions.