Patent quality and research productivity: Measuring innovation with multiple indicators

We analyse the determinants of the decline in research productivity using panel data on manufacturing firms in the US for the period 1980-93. We focus on three factors: the level of demand, the quality of patents and technological exhaustion. We develop an index of patent 'quality' using detailed patent information and show that using multiple indicators substantially reduces the measured variance in quality. Research productivity at the firm level is inversely related to patent quality and the level of demand, as predicted by theory and patent quality is positively associated with the stock market value of firms.