TAKEN at face value, two recent developments on the charter-school front - at the national and state level - might be considered positive ammunition for those championing alternatives to traditional public schools.

Last week, Stanford University's Center for Research on Education Outcomes released a new report that studied charter-school performance in 41 urban areas, including Philadelphia. It found that such charters provide higher levels of growth in math and reading compared to traditional public schools.

That doesn't necessarily mean that charter students are pulling higher scores, but that their level of improvement is outpacing those of their traditional-school peers. One reason: Charter students are getting more instruction in math and reading; the equivalent of 40 days and 28 days, respectively.

At the state level, the House passed a bill that would institute some charter reforms. Since virtually no reform has occurred since the 1997 law authorizing charters, this could also be considered good news.

The reality on both fronts is more complicated.

Pennsylvania and many other states have seen aggressive growth of charter schools, but too often the data on their effectiveness is confusing or contradictory. That may always be the case, since even if students of similar demographic backgrounds are compared, there are significant enough differences between traditional public schools and charters to make comparison hard.

Two such areas, according to Kate Shaw, of Philadelphia-based Research for Action, which has undertaken many education studies, are in special education and students who live in poverty. Traditional public schools typically have more students with high needs in special education and more students experiencing extreme poverty with far more risk factors than charter counterparts. That, Shaw says, can make direct comparisons between traditional and charter schools problematic.

In 2013, a CREDO study of charter schools in urban and non-urban areas was far more mixed: Pennsylvania charter students on average were lagging behind students in regular public schools; almost half the states' charter-school students did worse academically than their traditional public school peers.

"Mixed" is a word we would also use for Harrisburg's reform bill, passed by the House last month. On the plus side, it would alter the funding for cyber charter schools, permitting school districts to deduct food-service costs from the money they pay to cyber schools. That's a common-sense change. It also would cap the money that charters are allowed to keep as fund balances - some of them currently in the millions.

But it would also prohibit districts from establishing caps on enrollments in the charter agreements they enter into. Charter caps are already prohibited - which is in itself worth reforming - but now, even those necessary controls can't be incorporated in the operating agreements that districts make with charters.

Gov. Tom Wolf is also proposing reforms that are more significant. One would restore some reimbursement for charter costs to districts, another would cap the amount of per-student allocation for cyber charters to $5,950.

The state has nearly two decades of charter-school education under its belt. Getting a better handle on what we have actually learned and what changes we need to make should be a priority for everyone, not just those in Harrisburg.