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Class Size, Teacher Hours and Educational Attainment*


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    We are grateful to Hans Bonesrønning, Christian Dustmann, Caroline Hoxby, Costas Meghir, Per Pettersson-Lidbom, Ludger Woessmann and two anonymous referees for helpful comments. The Danish Social Science Research Council is gratefully acknowledged for support. Browning thanks the Danish National Research Foundation for funding through its support to the Centre for Applied Microeconometrics (CAM), University of Copenhagen. A working paper version with more details on data and estimation results is available from the authors on request.


We employ a regression-discontinuity design to identify effects on educational attainment after compulsory school of class size and the number of pupils per weekly teacher hour using administrative rules as instruments. We use Danish administrative panel data. Average class size is 20, about the same as in the US and most European countries. Restricting the sample to observations close to the enrolment discontinuity points where the administrative rules have greatest predictive power, instrumental variables estimates are consistently negative. Estimates from the preferred specification are marginally significant and indicate modest effects in line with earlier studies. Estimates for subgroups are less precise, but they indicate larger effects for pupils from less advantaged backgrounds.