Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
Directed technological change (DTC) concerns how stocks of factor-augmenting knowledge evolve relative to each other. We model investment in factor-augmenting knowledge at firm level, and show that relative investment rates depend on the relative factor shares and elasticities. Furthermore, we argue that links between the knowledge stocks and substitution between final goods are crucial to the long-run evolution of the economy.