"In all the numbers Rhee's critics have assembled, the two facts that stand out have nothing to do with test scores, but rather with student and teacher absenteeism. One does not know how quickly leaders can have an impact on student learning, but strong educational leaders are known for their impact on school culture. If we take Rhee at her word, changing culture was what she was trying to do, and those falling absenteeism indicators suggest that she may have had an effect, even in a short period of time. It's even possible that a change in the D.C. school climate accelerated learning gains. About that one cannot be certain when only two years of NAEP data are available. But one can be quite sure that a case against Rhee has yet to be established."