In an extension of the standard approach, the authors allow for endogeneity of production decisions, heterogeneity of R&D elasticities, and asymmetric treatment of intramural and extramural R&D. The empirical analyses are based on an extended Cobb-Douglas production function that allows for firms with zero R&D capital, which is especially useful for studying firms’ transition from being R&D-non—active to becoming R&D-active. Using a large panel of Norwegian firms observed in the period 2001-2018, the authors estimate the average private net return to be in the range 0-5 percent across a variety of model specifications if we treat intra- and extramural R&D symmetrically. If in compliance with the Frascati manual, they treat intramural R&D as investment and extramural R&D as intermediate input, the estimated net return increases to 5-10 percent.
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