Source: Mckinley L. Blackburn, Industrial Relations, Volume 47 Issue 3, July 2008
From the abstract:
This paper addresses several estimation and specification issues in estimating union wage differentials in the United States over the last two decades. Estimates provide strong evidence of a decline in the differential for women. For men, the differential appears to have declined for a person with overall average characteristics, but not for a male with characteristics of the average unionized male.