Sol Stern offers a wise suggestion in this City Journal Online piece: create an independent agency in New York to verify student achievement results.
In campaigning for mayoral control in 2002, Bloomberg made New Yorkers an offer they couldn't refuse: Give me the sole authority to improve the schools, and then hold me accountable for the results. The mayor promised to give taxpayers a bigger bang for their education buck. If he failed to deliver on that promise, the public would at least know that it was his failure and could vote him out of office... The problem was that the legislation failed to ensure that voters would have access to unimpeachable information about student achievement, a prerequisite to any reasoned judgment about how well the schools were doing under the new regime.
One might point out that state departments of education are supposed to play this role--providing unimpeachable information about student achievement--but it may be that these agencies are too weak and big-city systems too strong for this governance arrangement to work out in practice. So bring in the independent green-eye-shade types, and let the truth be known. But don't expect the arguments over "what the data show" to cease. These are New Yorkers we're talking about, after all, who subscribe to the maxim, "I bicker, therefore I am."