Do all boats rise when charter schools expand?

I. A Hypothesis 

All organizations are founded on a hypothesis. Deliberate organizations are explicit about their hypothesis.

The City Fund’s hypothesis is that educational opportunity in cities will increase if:

(1) Non-profit schools enroll more students.

(2) Cities adopt a unified enrollment system to increase equitable access to all public schools.

(3) Elected officials encourage the best schools to expand and selectively transform struggling schools with new non-profit operators.

We don’t yet know if this is true, though early signs are promising.

Cities such as New Orleans, Denver, Newark, and Washington D.C. have seen strong gains using these strategies (as well as a focus on instruction and talent in district schools).

II. Fordham’s New Study on Charter Enrollment 

Fordham just put out a study that attempts to measure whether increases in charter enrollment in a city leads to all students learning more, including children in district schools.

Fordham found that, in urban areas, higher charter schools enrollment is associated with achievement gains for all black and Hispanic students in the city.

If it holds, this is an important finding on the benefit of expanding non-profit schools.

So how much weight should we give to the study?

On the positive side, the authors methodology is reasonable: they track a bunch of cities that are home to increasing charter enrollment, and then use a set of controls to try and determine if this increase in enrollment is associated with positive citywide results for minority students.

There are some clear limitations to this approach, most of which the authors acknowledge. The trickiest issue is causation: it’s hard to know if charter enrollment itself is causing the gains. For example, perhaps cities that see increasing charter enrollment also tend to be home to strong economic growth, and it’s the city’s economic gains that are driving better student performance.

Another major limitation is how much we can extrapolate from the cities in the data set.

Given that very few cities rapidly grew charters (ie, went from 10% enrollment to 50% enrollment), it’s hard to know how much we can draw from the study.

Perhaps citywide gains spike when charters increase from 10% to 30% (due to increased competition) but then reverse when charters go from 30% to 60% (due to financial pressures on the district). We won’t know until more cities reach higher charter enrollment.

III. What Can We Learn From the Study? 

The Fordham study should nudge us a bit toward the idea that increasing charter enrollment can increase learning for all students.

But, perhaps more importantly, it should cast serious doubt on the claim that the current rate of increased charter enrollment is significantly harming traditional public schools.

We can’t know if increased charter enrollment is causing citywide gains, but we can clearly observe that current charter enrollment is not causing major drops in district performance.

This is a very important finding. It refutes the major argument made by charter detractors.

This result mirrors some of what we’ve seen in CREDO’s recent analysis of city performance.

CREDO found an all boats rising effect in three of the most mature choice cities in the country. In Denver, Camden, Washington D.C., district schools improved as the charter enrollment increased.

It’s notable, though not dispositive, to us that these cities all have unified enrollment systems and transparent school performance information.

IV. How Can We Learn More?

Doug Harris and his team at Tulane are going to attempt a similar study but use a quasi-experimental approach. This should shed some more light on the issue.

We will also keep working with CREDO to hold the mirror up on the cities The City Fund is working most deeply with.

Lastly, it’s worth mentioning that understanding citywide impacts is important but not the only way to understand charter growth.

We should care a lot about the fact that charter school enrollment is increasing in the first place: it’s a clear sign that families are hungry for a better public education for their children. And that they view charter schools as way to meet their children’s needs.

Large scale correlational studies are not a substitute for simply observing that millions of parents are choosing charter schools in hopes of finding a great school for their children.

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