between imitation and innovation. Using US patent data for the period 1977-2005, we find that there are inverted U …-shaped relationships between the degree of industry-level technological imitation and industry-level innovation activities and between the … degree of industry-level technological imitation and the value of firm-level innovation. Our results suggest that positive …

In active investment climates where firms sequentially improve each other's products, a patent can terminate either … because it expires or because a noninfringing innovation displaces its product in the market. We define the length of time … until one of these happens as the effective patent life, and show how it depends on patent breadth. We distinguish "lagging …