Do they identify bad schools? Or do they identify schools with children that are harder to teach?
This is a genuine question.
I'm also a bit disappointed about the lack of rigorous evidence base with education. (Well, with everything, really.) In the UK the Department for Families and Schools has a lot of power over education. In theory that should help with an evidence base because they should be flowing good research down through to schools. But there's such a political atmosphere about teaching that interference from government is often seen as unwelcome. And, sometimes, that attitude is correct be government is suggesting something that's stupid.
There's also a problem that bad teachers are difficult to remove from teaching.
Do they identify bad schools? Or do they identify schools with children that are harder to teach?
Test results are a measurement of how well educated the student is at a point in time. That's all.
You can measure the effect of a school by studying value added - how well a student performs after education compared to how well they performed before. Or similarly, how well a student performs compared to statistically similar students.
You can determine that some subsets of students are harder to teach by correlating observable characters (parental income, race, gender, etc) with outcomes.
Everything you mention is technically possible but it's unclear that they are actually well used, with considerable evidence (see NYC's recent data release) that the numbers are used by people who are completely unprepared to work with complex data.
Even the value add comparisons are hard to draw correct conclusions from without more context: a student shows no improvement in math. Did they have a bad teacher, an attendance problem or was it something like being an ESL student who has never received the help needed to understand their classes? That's not the kind of analysis which happens when the tests are effectively a single number which determines careers.
Tell you what - lets eliminate all government accountability, since we can't avoid politicians/reporters/etc mangling things. End the FOIA, CBO, GAO, etc? Shut down thomas.loc.gov, and stop reporting the federal budget?
Or maybe we can accept that nothing is perfect, and stop letting perfection be the enemy of the good.
There's a difference between something being "not perfect but useful" and something being "not perfect and harmful".
Since there's very little research on the benefits or disadvantages of constant testing it's surprising that people are happy to spend so much time and money on it.
This is a genuine question.
I'm also a bit disappointed about the lack of rigorous evidence base with education. (Well, with everything, really.) In the UK the Department for Families and Schools has a lot of power over education. In theory that should help with an evidence base because they should be flowing good research down through to schools. But there's such a political atmosphere about teaching that interference from government is often seen as unwelcome. And, sometimes, that attitude is correct be government is suggesting something that's stupid.
There's also a problem that bad teachers are difficult to remove from teaching.