resources. A change in the price of a related resource will affect the demand for labor. For example, automobiles can be assembled with varying combinations of labor and machinery. If the price of machinery falls firms will tend to substitute machines for labor and the demand for labor will fall. If labor and machinery are used as complementary resources and the price of machinery falls then more machinery will be bought and more workers will be needed to run the new machines, causing the labor demand curve to shift out.

Price elasticity of resource demand (PERD)