Advantage for voucher schools?

A study by Jonas Vlachos, Stockholm University and affiliated to IFN, and Björn Tyrefors Hinnerich, has created debate in Swedish media. Vlachos and Tyrefors find that students at upper-secondary voucher schools on average score 0.06 standard deviations lower on externally graded standardized tests. At the same time voucher schools are 0.14 standard deviations more generous than municipal schools in their internal test grading.