This paper applies a production function approach to the analysis of imperfection in product and factor markets and develops a test of Efficient Bargaining for wage and employment determination. Based on a translog function defined at the firm level, estimates for the Belgian chemical industry are consistent with the existence of product market power which is significantly eroded by union wage rents.
Bughin, J. (1993). Union Firm Efficient Bargaining and Test of Oligopolistic Conduct. The Review of Economics and Statistics, 75(3), 563-567. https://doi.org/10.2307/2109477 (Original work published 1993)