Does union membership really reduce job satisfaction?

"We investigate the effect of union membership on job satisfaction. Whilst it is common to study the effects of union status on satisfaction treating individual membership as given, in this paper, we account for the endogenous selection induced by the sorting of workers into unionised jobs. Using linked employer-employee data from the 1998 British Workplace Employee Relations Survey, we address the question of how the membership decision is related to overall job satisfaction and to satisfaction with pay. Once the endogeneity of membership is accounted for, the marked difference in job satisfaction between unionised and non-unionised workers characterising raw data disappears, indicating that a selection effect, rather than a causal effect, explains the relationship"--London School of Economics web site.