Studies by Farber and by Freeman suggest that
a. shrinking union wage premiums have made it easy for firms to employ anti-union tactics.
b. about 40% of unions' decline can be explained by structural changes in the economy.
c. recent NLRB rulings have been increasingly favorable to unions and should stop the decline in their membership.
d. managerial opposition has been steady over the years, and has not contributed to the decline of unionization.
