Did N.Y.C. Charter Study Have a Selection Bias?

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To the Editor:

Your Sept. 30, 2009, article "N.Y.C. Study Finds Gains for Charters" begs an important question about the recent study on New York City charter schools’ academic outcomes: What about the background variable of students’ English-language proficiency?

In New York, current English-language learners, or ELLs, make up 14 percent of the city’s public school population, but only 4 percent of its charter school enrollment. Former ELLs make up another 14 percent of the overall public school enrollment. But the study conducted by Stanford University researcher Caroline M. Hoxby and her colleagues compares the academic outcomes of only those students who applied to New York’s oversubscribed charter schools: those who gained admission vs. those who did not.

What if parents of ELL students do not apply for charter lotteries because of lack of knowledge regarding the options, poor outreach by charter operators to ELL/immigrant parents, lack of information in native languages for parents of ELLs, lack of ELL-instruction-program services in most charters schools, and low numbers of qualified (read certified) ELL teachers in charter schools? These are conditions I am acutely aware of as a longtime New York City-based policy analyst and ELL advocate.

If these conditions apply, then the comparison regarding the relative success of students in charter schools vs. those in traditional public schools is biased. Again, a relevant question to ask is: Do the study’s authors take into account this selection bias in their research on charter school students’ academic outcomes?

Luis O. Reyes
Research Associate
Center for Puerto Rican Studies
Hunter College
City University of New York
New York, N.Y.

Vol. 29, Issue 07, Page 24

Published in Print: October 14, 2009, as Did N.Y.C. Charter Study Have a Selection Bias?
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