Are Charter Schools Dramatically Outperforming Public Schools? A New Report Says Look More Carefully

At Forbes, a look at the new Network for Public Education critiques of that CREDO report claiming that charters show remarkable gains over public schools. For instance:

CREDO finds charters come out ahead by 16 days of learning for reading, and 6 days of learning for math. That translates 0.011 and 0.028 standard deviations over traditional public schools.

But is that a remarkable difference?

To answer that question, NPE turned to another CREDO report.

In reading, charter students, on average, realize a growth in learning that is .01 standard deviations less than their TPS counterparts. This small difference — less than 1 percent of a standard deviation — is significant statistically but is meaningless from a practical standpoint. Differences of the magnitude described here could arise simply from the measurement error in the state achievement tests that make up the growth score, so considerable caution is needed in the use of these results.

In math, the analysis shows that students in charter schools gain significantly less than their virtual twin. Charter students on average have learning gains that are .03 standard deviations smaller than their TPS peers. Unlike reading, the observed difference in average math gains is both significant and large enough to be meaningful. In both cases, however, the absolute size of the effect is small.

In other words, when a study found charter schools behind traditional public schools by that amount, CREDO found the effects “meaningless” and “small.”

Read the full piece here.