Rahm Emanuel's declaration about the best-performing high schools turns out to be a lightning rod—though not necessarily attracting the folks you'd expect, like the Chicago press.

It did raise the hackles of charter opponents like Don Moore of Designs for Change. According to Moore, Emanuel implies that charters have good results across the board. But no matter how you manipulate school performance data, that doesn't ring true—especially Emanuel's "seven best performing schools" remark: "No way," says Moore, "that you can make it work."

That didn't stop me from trying.

On the CPS Web site, for example, I found measures of high-school student test-score gains from freshman to junior year.

Using this criterion (taking a composite of English, reading, math, and science scores), five of the ten top-scoring Chicago public high schools are charters. Nine of the ten limit their enrollment; the tenth school is what CPS calls a "neighborhood" school: it must take all comers.

So which data did Emanuel use?

As I reported elsewhere, Emanuel spokesman Ben LaBolt sent me a spreadsheet that ranks schools by "scores" (with Northside on top with 100).

I tried comparing Emanuel's spreadsheet to CPS data on-line—making myself dizzy—but I couldn't find any data that had scores matching the ones LaBolt sent me.

When I asked which data set the campaign used, the campaign said the data came from a spreadsheet on another CPS Web page—but neither that set of data nor the earlier one seems to jibe completely with Emanuel's remark.

It's been pointed out to me that one could find a way to manipulate school-performance data to support just about any charter claim, including Emanuel's. I couldn't, though—which I guess is the point.

No wonder that Emanuel's claim didn't get reported by Chicago's major news-media types.

Then I talked to a few of them—off the record, as they insisted. So while I can't reveal details, they don't seem daunted by the data.

For his part, spokesman LaBolt was anything but adamant about Emanuel's charter remark. "Our policy's not even based on it," LaBolt told me. "If you've got better data, we're happy to use it."

Reporters: Remember that come May.