Local context matters. It's true when it comes to teacher shortages, and it shouldn't come as a surprise that it would be true when it comes to teacher retention, too.

A recent study by John P. Papay (Brown University) and colleagues investigated teacher retention rates in 16 urban school districts. The researchers found that the districts in the study retain on average 55 percent of teachers after five years. What this average hides, however, is substantial variation across the districts. While one district only keeps 43 percent of its teachers after five years, another keeps 64 percent—not an insignificant difference.

The variation across districts held true even when the researchers considered a districts' ability to attract teachers back to the district who have left or keep the right teachers. Accounting for returning teachers (teachers who left the district and later came back) boosted teacher retention rates by as little as 5 percent to as much as 13 percent. When it comes to retaining high performers, one district kept 20 percent more of their high fliers than their low performers; in another district, this differential was only 7 percent.

This level of variation inevitably leads to this question: what district characteristics predict high retention rates? The researchers found no systematic relationship between teacher retention and basic district characteristics such as student demographics or eligibility for free and reduced price lunch, but they did not dig into what some districts are doing to better retain teachers. We don't learn why some districts have less turnover than others, but we do learn that only looking at averages can mask variation on a given issue at the school district level.

Want to know what we think districts can do to better retain teachers? See our Great Districts for Great Teachers initiative.