Using a substitution property of worker’s types (productivity and time preference), we propose an explanation for both fixed-wages and wage differentials. Fixed-wages result in bunching at the optimum. Equally productive workers with different time preference accept different wages.

In some cases spot markets failure to govern to whole or a part of the marketing channel effectively and contractual relations are gaining more importance. It is especially true in case of agricultural markets, since these markets became more differentiated and market players are vulnerable in...