What's behind the movement toward meaningless school ratings?

The state's new color-coded school rating system debuted with a resounding thud.  The mediocre to failing scores it assigned to districts and individual schools in Ann Arbor, Okemos, East Lansing and other high-performing schools was so patently absurd, many reacted with disinterest.  After all, who would pay any attention to a system which is so obviously getting it wrong?  However, systems like Michigan's with a bias to favor small charter schools have cropped up in other states as well, and in at least one case, the bias was proven to be by design.

The Associated Press uncovered emails which showed Indiana's chief education official rigged their system to protect a particular charter school:

INDIANAPOLIS — Former Indiana and current Florida schools chief Tony Bennett built his national star by promising to hold "failing" schools accountable. But when it appeared an Indianapolis charter school run by a prominent Republican donor might receive a poor grade, Bennett's education team frantically overhauled his signature "A-F" school grading system to improve the school's marks.

Emails obtained by The Associated Press show Bennett and his staff scrambled last fall to ensure influential donor Christel DeHaan's school received an "A," despite poor test scores in algebra that initially earned it a "C."

"They need to understand that anything less than an A for Christel House compromises all of our accountability work," Bennett wrote in a Sept. 12 email to then-chief of staff Heather Neal, who is now Gov. Mike Pence's chief lobbyist. [Tony Bennett, Former Indiana School Superintendent, Changed Top GOP Donor's School's Grade, Huffington Post, July 29, 2013.]

Like the Indiana system, Michigan's system has a heavy bias to small charter schools.  According to analysis by education blogger Martha Toth, Michigan's system scored more than 97 percent of districts and schools "yellow" or lower ... failing grades.  Report Cards that Offer Zero Useful Information, Education Matters, Sept. 3, 2013.  Of the very few "green" schools, many qualified merely by being a tiny charter school:

Of the 135 green schools, 41 (nearly one-third) got “zero of a possible zero points” — so how is it that they are rated green? Most are so designated on the basis of three-year participation rates (how many children actually took the tests) and “compliance factors” (planning and reporting requirements that earn no points). They have no student test scores because all their grade cohorts are under 30 pupils — a prime indicator that they are likely to be charter schools. Other “green” schools with very low point totals got them for such factors as student attendance. [Id.]

While Michigan's system may be peculiar, it's certainly not unique.  And although the results are clearly meaningless, this is an issue that warrants close scrutiny from public school advocates.