Teacher and writer Matt McCabe wrote a thoughtful response to my earlier post about the market in high schools, including four pieces of constructive criticism (I paraphrase):

1. Including selective enrollment schools in the pool of data will skew results to make it look like there is not much self selection for students to move to the top schools.
2. Using ACT growth over three years would better measure of educational quality than just the junior-year ACT score.
3. High school is geographically constraining; good schools may be far away.
4. New schools don’t have a record for parents to make decisions based on, and ACT scores aren’t the only things that matter to parents.

All of this seems right to me. In fact, I mention points 1 and 3  in the original post, but I don’t think that’s an “issue” as much as it suggests that Matt and I are thinking of slightly different questions. It may in fact be the case that, with fewer constraints, parents would create a more functional market than currently exists. But my point wasn’t that parents were failing to make the right choices: it was that, for whatever reason, the market is failing to push students towards the district’s best schools. If the reasons turn out to be structural – as it seems that Matt and I agree it is, largely – that seems just as serious a problem. If parents were the issue, we might hold out hope that they would make better decisions with better information or a more streamlined application process. But if the best schools – not just the best, but a huge percentage of even acceptable schools – are either 1) gated to all but the highest-achieving students or 2) unreasonably far away, it doesn’t seem super clear what realistic market-based solutions there are to that.

Point 2 is just right: that would have made a better analysis, and I didn’t do it mainly because it would have taken much more time. I think what I did is enough to establish the basic idea, though.

Point 4 is I think the most interesting. Why, exactly, do parents send their kids to new, unproven charter schools? What sorts of qualities offset poor testing performance? I don’t know. I would love to hear what parents, teachers or administrators have to say about that, because it seems like a question that would be difficult to answer with data.