Rankings at Risk: Data error leads to change in school ratings

A data analysis error has led to large revisions in the Texas non-profit advocacy group Children at Risk’s annual rankings of schools.

The Houston Chronicle reported on May 19 that a miscalculation in the organization’s “growth index” rating led to the errors in the final rankings. The growth index measures improvements in a school’s annual standardized test scores over time.

Most schools shifted in the rankings slightly, but nearly 25 percent of elementary schools and half of middle schools in the Houston metro area saw large shifts in their ratings – moving more than a half a grade in Children at Risk’s rating system (e.g. from a B+ to a B). Campuses above the 75^th percentile received an “A” grade, while those below the 15^th percentile received an “F.”

Children at Risk’s ranking methodology can be found on the group’s Web site. The rankings themselves are available here.

The large swings in ratings based on the error in one component may call into question the underlying validity of the ranking system.

In the Houston Independent School District, Bush and Roberts elementary schools jumped more than 50 spots in the rankings. Locally, River Oaks Elementary School saw a large boost its ranking, jumping from 44 to fourth among the 814 elementary schools rated in the Houston region. HISD’s T.H. Rodgers and Lanier middle schools remained in the top 10 middle schools of 314 in the metro area, with Rodgers ranked first and Lanier ranked eighth.