The labor income Shares, the Price Markup, and the Elasticity of Substitution Between Capital and Labor

The labor income share is constant under the assumptions of a Cobb-Douglas production function and perfect competition. This paper modifies these assumptions, and investigates how to behave actually dynamic the labor income share within the Iranian manufacturing industries through estimating the elasticity of substitution between capital and labor and the price markup. This paper estimates such elasticity by using of a CES production function under perfect and imperfect competition in the product market. The degree of imperfect competition is measured following the Rojer approach. This dynamism in labor income share is explained by (1) a non-unitary elasticity of substitution between capital and labor; and (2) non-perfect competition in the product market. The results show that the elasticity of substitution is 0.75 under perfect competition without price markup, but it is 0.65 under imperfect competition with price markup. These mean that the elasticity of substitution decreases due to the presence of the price markup in imperfect competition regime, while labor income share increases highly by increase in capital intensity.