Estimating Price- Cost Margins and Scale Economies from a Panel of Microdata

Hall's (1988) approach to study price- cost margins is adapted to simultaneously estimate price- cost margins and scale economies from a panel of plant level data. The paper shows how this methodology provides a very flexible framework with only a few, economically interesting parameters to be estimated. The econometric model is tested and estimated on different panels of plants, covering most manufacturing industries in Norway 1980- 90. The GMM- estimates suggest significant, but quite small, markups in all industries. No industry exhibits increasing returns to scale; the average firm (in all industries) seems to face constant or moderately decreasing returns to scale. Estimates suggest that there is more variation in the price- cost margins and scale coefficients within the fairly narrow industry groups investigated, as compared to between the industry groups.