What has happened to the union wage differential in Britain in the 1990s?

Using the BHPS for the years 1991 and 1995 this paper finds that the union wage differential has declined for the private sector workforce. For males the decline was notable but not significant; for females the decline in the union member wage differential was significant. This decline mainly affected the white collar, service sector of the economy for both males and females. The decline was significant for white collar females. Female union members in blue collar jobs experienced a significant decline in the wage differential. In the 'traditional' union areas of male, blue collar, production sector jobs, the union wage differential maintained itself, or even increased. In terms of altering wage inequality the decline in the female union member wage differential chiefly affected members in the upper part of the wage distribution. Overall, the longitudinal results indicated that selection effects for male workers as a group were not well defined. Female workers are negatively selected into membership across the whole sample. Female workers require union membership to maintain their pay.