The United States Steel industry underwent a major paradigmatic shift between the 1950s and 1990s. According to George Stigler, the integrated steel industry had a fairly high level of concentration at the time US Steel was formed. According to Louis Marengo, the steel industry used "a multiple basing point system" for pricing its products until 1948. Walter Adams and Joel Dirlam identify two non-price avenues for the steel industry to react to import competition. One was that United States firms were lagging behind the world in using technology such as the basic oxygen furnaces and continuous casting technology. The other was that the firms could seek protection through lobbying. The traditional model of welfare benefits seeks a net benefit estimate through consumer surplus via trade liberalization. Traditional computational general equilibrium models lump the steel industry with other industries.