Returns to scale effect in labour productivity growth

Economists acknowledge that technical progress and growth in capital inputs increase labour productivity (LP). However, less focus is given to the realization that changes in labour input alone could also affect LP. Because this effect disappears when the short-run technology exhibits constant returns to scale, we call it the returns to scale effect. We decompose growth in LP into three contributing factors: (1) technical progress, (2) capital input growth and the (3) returns to scale effect. We propose theoretical measures for these three components and show that they coincide with the index number formulae consisting of prices and quantities of inputs and outputs. Subsequently, we apply the results of our decomposition to US industry data for 1987–2009. LP in the services sector is shown to grow much slower than that in the goods sector during the 1987–1995 productivity slowdown period. We conclude that the returns to scale effect can considerably explain the gap in LP growth between the two industry groups.