The state's top-to-bottom listing of schools is less a measure of school quality and more a measure of student poverty, according to a report from the conservative think tank the Mackinac Center for Public Policy.

The report says the Michigan Department of Education’s "Top-to-Bottom" method of ranking public schools is flawed because it correlates too closely with poverty rates and does not give schools that serve low-income students enough credit for learning gains made by those students Report author, Audrey Spalding, says 55 percent of a school’s ranking on the 2012-13 TTB list can be explained by the number of students who qualify for a free school lunch.

She says the correlation is significant because those rankings can be used to impose consequences on low-ranking schools.

But Department of Education spokesman Martin Ackley says he doesn't think the top-to-bottom rankings are flawed, adding "they're designed to identify specific education thresholds in schools."

He also points to the existence of Beating the Odds schools, schools that are exceeding improvement targets despite poverty and other potential handicaps, shows that the measures are accurate.