Copenhagen Business School, Department of Strategy and Innovation, Frederiksberg 2000, Denmark.
Massachusetts Institute of Technology, Cambridge, MA 02139.
Proc Natl Acad Sci U S A. 2023 Sep 5;120(36):e2200684120. doi: 10.1073/pnas.2200684120. Epub 2023 Aug 28.
STEM PhDs are a critical source of human capital in the economy, contributing to commercial as well as academic science. We examine whether STEM PhD students become new inventors (file their first patent) during their doctoral training at the top 25 U.S. universities (by patenting). We find that 4% of PhDs become new inventors. However, among PhDs of faculty who are themselves top (prolific) inventors, this figure rises to 23%. These faculty train 44% of all the new inventor PhDs by copatenting with their advisees. We also explore whether new inventor PhDs are equally distributed by gender. In our university sample, the female share of new inventors is 9% points (pp) lower than the female share of PhDs. Several channels contribute to this: First, female PhDs are less likely to be trained by top inventor advisors (TIs) than male PhDs. Second, they are less likely to be trained by (the larger number of) male top inventors: The estimated gap in the female % of PhDs between female and male TIs is 7 to 9 pp. Third, female PhDs (supervised by top inventors and especially by other faculty) have a lower probability of becoming new inventors relative to their male counterparts. Notably, we find that male and female top inventors have similar rates of transforming their female advisees into new inventors at 4 to 8 pp lower (17 to 26% lower rate) than for male advisees. The gap remains at 4 pp comparing students of the same advisor and controlling for thesis topic.
科学、技术、工程和数学（STEM）领域的博士是经济中人力资本的重要来源，他们不仅为学术科学，也为商业科学做出贡献。我们考察了顶尖 25 所美国大学（按专利数量）的博士研究生在攻读博士学位期间是否会成为新的发明者（提交他们的第一项专利）。我们发现，有 4%的博士生成为了新的发明者。然而，在本身就是顶尖（多产）发明家的教师的博士生中，这一比例上升到 23%。这些教师通过与学生合著专利，共同培养了 44%的新发明博士生。我们还探讨了新发明博士生是否在性别上均等分布。在我们的大学样本中，新发明博士生中的女性比例比博士生中的女性比例低 9 个百分点（pp）。有几个因素导致了这一现象：首先，女博士生接受顶尖发明家导师（TI）培训的可能性比男博士生低。其次，她们接受男性顶尖发明家培训的可能性也较低：女性 TI 和男性 TI 之间的女博士生比例差距估计为 7 到 9 个百分点。第三，与男性相比，由顶尖发明家（尤其是其他教师）指导的女博士生成为新发明的可能性较低。值得注意的是，我们发现，男性和女性顶尖发明家将他们的女性学生转化为新发明家的比例相似，比男性学生低 4 到 8 个百分点（17%到 26%的比例较低）。在比较同一导师的学生并控制论文主题的情况下，这一差距仍为 4 个百分点。
