How do employee training and knowledge stocks affect product innovation?

The main purpose of this paper is to explore how interactions of knowledge flows and knowledge stocks could shape firms' innovative performance. Knowledge flows are measured on the grounds of human resource training practices while different levels and forms of knowledge stocks (i.e. educational attainment, exporting activity, and firm age) are considered. We make use of two-period panel probit regressions and a rich data survey of the 524 largest Greek manufacturing firms conducted in two waves (2011 and 2013). Our findings suggest that the beneficial effects of knowledge flows strengthen when knowledge stocks accumulated by employees' education and firm age are low. When knowledge stocks are limited, knowledge flows can act as a bridge for product innovation. On the contrary, when knowledge stocks are high, higher investments in knowledge flows may lead to diminishing returns and, thus, to decreased innovation performance beyond a certain point.