The nationwide push for privatization of education through corporate-backed charter schools received a rebuke this week after newly calculated data in Pennsylvania showed that such schools are markedly out-performed by their public counterparts.

Both brick-and-mortar charters and online institutions called "cyber charters" came up short in comparisons with traditional public schools. 

As the Philadelphia Inquirer reports:

The percentage of Pennsylvania charter schools that met academic benchmarks plummeted after the state Department of Education was forced to recalculate the performance rates.

Under a new and controversial method the department used last fall, 49 percent of 156 charter schools met benchmarks based on student tests scores in 2011-12.

The rate dropped to 28 percent after the department released a recalculation this week. In Philadelphia, the percentage of the 80 charter schools that met the standards declined from 54 percent to 29 percent.

None of the 12 cyber charter schools that provide online in-home instruction to students statewide met the benchmarks. Previously, one met the standard.

As the state's association of school boards said in a statement, its members "had expressed concerns that [the earlier calculations were an] attempt to artificially inflate the number of charter schools regarded as making annual yearly progress (AYP)"--a key measure of a school's success in this age of high-stakes testing and amid mantras of "accountability."

In addition, the group suggested, the attempt may have been an effort "to mask deficiencies in charter schools," but that charter school advocates repeated insistence that charter schools are the solution to education reform should mean that "academic achievement issues" should be critical considerations in the charter school renewal process.