Wisconsin’s long-running private school voucher program has drawn decades of research interest, including a recent report from School Choice Wisconsin. The report claims voucher-receiving schools in Racine, Milwaukee, and statewide are far more cost-effective than public district schools. But its analysis is not just flawed—it’s wrong. Cost-effectiveness ratios are inappropriate for comparing schools serving different student populations, and further errors in spending, outcome, and demographic data compound the problem. In short, School Choice Wisconsin conducted the wrong analysis in the wrong way, making the report useless for policymaking.