A new study of Pennsylvania charter schools released Monday finds teachers who ply their trade in schools that are part of charter management organizations (CMOs) are more effective than their counterparts in both traditional public schools and stand-alone charter schools.

Many previous studies have found charter schools outperform traditional public schools. A recent study in the journal Education Next, for example, found charter school students made greater gains on national assessment test results from 2005 to 2017 than traditional public school students. This new study takes a different approach by comparing the performance of charters that are part of CMOs to their independent counterparts, as well as traditional public schools.

The study by the Thomas Fordham Institute used data collected by the Pennsylvania Department of Education between 2007 and 2017. The data show that teachers in CMOs improve more quickly than they do in both traditional public schools and individual charters.

Noting that research shows new teachers are less effective than their experienced counterparts, “urban charter networks often outperform their district peers” despite having a higher percentage of junior staff. The study suggests that charter schools and CMOs help teachers improve their skills more quickly than traditional school settings.

The study, conducted by George Mason University associate professor Matthew Steinberg and University of Pennsylvania doctoral student Haisheng Yang, measures teacher performance in terms of the “value added” by their instruction to student test scores in math and English language arts.

“Although such estimates cannot capture other valuable aspects of teaching practice and behaviors, research shows that (in addition to learning more math and English language arts) students assigned to teachers with higher value-added scores are more likely to go to college and earn higher salaries later in life,” they said.

One reason for the difference in performance? A key feature of the charter school model is greater autonomy around human-capital policies than traditional public schools, the authors note.

There are a few caveats in the study that raise questions about the effectiveness of stand-alone charters unattached to CMOs. For example, that study finds that on average teachers in stand-alone charters are less effective in math than teachers in traditional public schools.

Teacher mobility also figures prominently into the conclusions drawn from the research, a significant issue given current turnover rates. Each year, American schools hire 200,000 new teachers, the authors note. “And because turnover rates have increased, 38 percent of K-12 teachers in the U.S. now have less than ten years of experience.”

Unsurprisingly, mobile teachers tend to be less effective than those who stay in the same classroom for a longer period of time.

While the study finds charters “struggle with teacher retention,” the data also shows “CMO’s retain and promote more effective teachers into leadership roles.”

Why did the researchers choose to study education in Pennsylvania as opposed to another state? The commonwealth is identified as “an ideal setting for investigating teacher effectiveness and mobility across the charter and traditional sectors,” for two reasons. One is the growth of charters in Pennsylvania over the last decade reflecting national trends. Another is the commonwealth includes a “robust and growing supply for both CMOs and stand-alone charter schools.

“Pennsylvania’s CMOs are succeeding with a fundamentally different approach to human capital than the state’s traditional public schools — an approach that relies heavily on recruitment, development and promotion to drive improvements in student-achievement outcomes,” Steinberg and Yang conclude. “Greater attention (should) be paid to the human-capital policies and practices implemented by charter schools in general and CMOs in particular.”