“…Intra-industry studies of the effect of unions on productivity and costs are more prevalent than inter-industry studies. These include the cement industry (Clark 1980a,b), construction (Allen 1984(Allen , 1986a(Allen ,b, 1988bCavalluzzo and Baldwin 1993), hospitals (Sloan and Adamache 1984;Register 1988), banking (Graddy and Hall 1985), coal (Connerton, Freeman, and Medoff 1983;Boal 1990;Boal and Pencavel 1994;Byrnes et al 1987), wooden furniture (Frantz 1976), machining (Kelley and Xue 1990), steel finishing (Ichniowski and Shaw 1995), and trucking (Delery et al 2000). Considering the studies prior to 1992, Belman (1992) concluded that the effects of unions on productivity and costs vary by industry and by the period under consideration.…”