To evaluate the relative performance of public vs. alternative school models, you have to adjust the test scores for the differences in all those factors that determine success. That is especially true because of what researchers call "selection bias." Parents have to choose to send their children to a charter school, meaning that charters start with students who have high parental involvement. If the charter school is newer or safer or has more technology, the difference in performance is expected to be significant.
Unfortunately, we don't adjust test scores for differences in factors such as intelligence, income, parental involvement, or school facilities. Instead, we use misleading, unadjusted test-score comparisons. That means some schools that test well might not be doing all they can, while those with failing scores might be making outstanding progress. We are largely clueless about what is happening.
Charter, Renaissance, Cyber, and other alternative school models are great ideas and may turn out to be the greatest thing for education since sliced bread. Or, they could wind up being a total disaster.
Unfortunately, we have no way of determining whether this massive educational experiment is succeeding. That is unfair to the new school models, the public schools, the taxpayers who fund all the educational approaches, and most important, our children.