Determinants of patent quality in U.S. manufacturing: technological diversity, appropriability, and firm size

We study the determinants of patent quality for a panel of U.S. manufacturing firms, focusing mainly on the effects of firm-level technological diversity and appropriability conditions. Technological diversity increases the quality-adjusted patent count on most of the diversity distribution, but its relationship with average patent quality is an inverted-U. We find that appropriability conditions (proxied by the rate of self-citations at the firm level) have similar, non-linear effects on both the average quality of patents, and quality-adjusted patents per R&D, which is consistent with an inverted-U pattern. Firm size has no effect on the average quality of patented innovation at the firm level. Finally, as R&D intensity increases, the rate of corporate innovation falls, but its average quality increases, indicating a quality–quantity trade-off in R&D.