“…The puzzle stems from the expectation that unions should in general enhance members' job satisfaction and wellbeing. A number of influential studies have established a link between unions and a pay premium and/or lower pay inequality (see, for example, Freeman 1980, Booth 1995, Gosling and Machin 1995, Clark and Oswald 1996, Card 1996, Card et al 2003, Budd and Na 2000, Metcalf et al 2001, Hirsch 2004, Blanchflower and Bryson 2004. Unions have also been linked to a number of other welfare improving changes for members, which include access to employer provided training (Booth 1991, Acemoglu et al 2001, Booth et al 2003, Waddoups 2012, risk sharing (Malcomson 1983), health insurance and pension plans (Buchmueller et al 2002), workplace and occupational health and safety (Donado and Walde 2012), family friendly policies (Budd and Mumford 2004), and curbing discrimination (Phanindra and Peled 1999).…”