[1] Royal Holloway Univ London, Dept Econ, London, England
[2] IZA, Bonn, Germany
[3] Inst Fiscal Studies, London, England
[4] Umea Univ, Umea, Sweden
[5] New Econ Sch, Moscow, Russia
[6] Stavanger Univ, Stavanger, Norway
[7] Simon Fraser Univ, Dept Econ, Burnaby, BC, Canada