Exploring the tail of patented invention value distributions

Patent renewal studies reveal a highly rightward-skewed distribution of patent values. Our approach elicits valuations approximating those of the patented invention. This paper focuses on the full-term patents of the application year 1977 held by West German and U.S. residents. The tail of skewed distributions values account for a large fraction of the cumulative value over all observations. Several tests were conducted to pin down more precisely the nature of the high-value tail distribution. Three highly skew alternatives were evaluated by graphical and maximum likelihood techniques: the two-parameter log normal, the one-parameter Pareto-Levy, and the three-parameter Singh-Maddala distribution. A two-parameter log normal distribution appears to provide the best fit to our patented invention value data.