Production functions provide a mapping from the firms' input quantity and productivity to output quantity. This mapping only generates unbiased estimates if input and output quality variation within and between observation units is accounted for. I review and classify state-of-the-art methods to...

The main thrust of this Element is a critical assessment of the theory and evidence concerning the sources of scale effects. It is argued that the analysis of static scale effects is important because scale effects are embedding in our world, and new technologies associated with an evolving...