Labor demand from the manufacturers, and labor demand determines in labor's marginal product (the MPPL). In a perfectly competitive market, in the short term, the vendors in order to get the most profit, must make the production has been carried out to real wages (W / P) is equal to the marginal product of labor that again. Similarly, the entire economic and social, the total demand for labor also decided that real wages equal the marginal product of that point, that is World Steel Pipe News , W / P = the MPPL World Steel Pipe News . Therefore, the dependencies between labor demand and the marginal product of labor, in fact, is the interdependence between the real wages of labor demand and labor relations. If the equal sign left of the N, a function of W / P, real wages, the labor demand function can be written
N = Nd (W / P)
labor demand is a decreasing function of real wages real wages are low, the demand for moving small labor demand; high real wages, labor demand is small.