[1] Univ Oxford, Med Sch, Dept Primary Hlth Care, Dept Primary Care, Walton St, Oxford OX2 6GG, England
[2] Univ Insubria, Dept Law Econ & Cultures, Varese, Italy
[3] Heriot Watt Univ, IZA Inst Lab, Edinburgh Business Sch, Edinburgh EH14 4AS, Scotland
[4] Univ Verona, Dept Econ, Via Cantarane 24, Verona, Italy