Therefore, workers who have those specific skills find it harder to find an alternative job. This makes the employers to invest more on specific training for the current employees. In competitive labor market, the workers receive the marginal product so the employers never invest in general skills as worker can easily change their job with those skills. .
Figure 2: Training with a compressed wage structure (Acemoglu and Pischke,1999) .
In oligopsony and monopsonistic competition, the main point here is that the wages are below the productivity of the workers which is W in Figure 1. (Acemoglu and Pischke,1999) This contradicts the perfect competition outcome and employers will be benefited with rents along with the assumption of fixed costs. This is why there is a possibility that oligopsony firm might pay for the general training of workers. Besides, the productivity function f(T) in oligopsony is steeper than the wage function w(t) that leads to a compressed wage structure in Figure 2 when the workers have greater level of skills. Firms earn higher profits over time as the gap between these two curves will be larger which is(T). Therefore, firms will want to invest more on the employers' training unlike in perfect competition the employer earns equal amount of profits from skilled and unskilled workers. (Acemoglu and Pischke,1999) Since the worker are not paid according to the marginal product eventhough their skills are general, the labor market imperfection turns the general skills to specific. (Acemoglu and Pischke,1999) Credit constraints can be another factor which allow employers to pay below the marginal product and regain training investment. .
The presence of transaction costs and asymmetric information are the imperfections in the labor market that form the rents and a compressed wage structure. It is costly for an employer to search employees and not easy for workers to find for a new job that is perfectly suitable for them.