Over at Charters and Choice, my colleague Katie Ash wrote about a new Government Accountability Office report finding big problems with charter schools reporting accurate enrollment numbers for English-language learners.

Her headline was: “GAO: Many Charter Schools Are Not Reporting Data on ELLs”.

The headline could have just as easily been: “GAO: U.S. Department of Education Fails to Provide Data Oversight”.

You could argue over which is more alarming: that charter schools aren’t appropriately reporting enrollment numbers of ELLs, or that the U.S. Department of Education does not examine the quality of data on a “regular basis,” as the GAO found?

The problem with the ELL data was that too many charter schools left the field blank when they were supposed to report the number of ELLs. Thirty-seven percent of charters, in fact, in school year 2010-11, had blanks in the field capturing ELL enrollment counts. Leaving a data field blank is very different than reporting a zero for enrollment.

In fact, in five states, the GAO found that between 80 percent and 100 percent of charter schools left ELL enrollment counts blank. That includes very-populous states such as New York and Ohio that are likely to have ELLs in charters.

The federal Education Department, for its part, did not perform any comprehensive data-quality checks to try to obtain better data, the GAO found. Federal officials, in a written response, said they are working on improving charter-school reporting.

The GAO has uncovered other problems with data at the Education Department, including that federal officials can’t say exactly what they collect. What’s more, the office for civil rights’ massive data collection from the 2009-10 school year was riddled with problems.

Obviously, when you collect data from tens of thousands of schools there are bound to be data errors. But it’s also important to note how important data has become to education policy—such as in trying to figure out how ELL enrollment compares in charters vs. noncharters. That’s a question that apparently can’t be answered right now.