The GSS is an unreliable indicator of biological sciences postdoc population trends

The postdoctoral research position is an essential step on the academic career track, and the biomedical research enterprise has become heavily dependent on postdoctoral scholars to conduct experimental research. Monitoring postdoc population trends is important for crafting and evaluating policies that affect this critical population. The tool most use for understanding the trends of the biological sciences postdoc population is the Survey of Graduate Students and Postdoctorates in Science and Engineering (GSS) administered by the National Center for Science and Engineering Statistics. To determine how well institutions tracked their postdocs, we analyzed the yearly changes in the biological sciences postdoc population at institutions surveyed by the GSS from 1980 to 2015. We find examples of large changes in the biological sciences postdoc population at one or a few institutions most years from 1980 to 2015. Most universities could not explain the data presented in the GSS, and for those that provided an explanation, the most common causes were improved institutional policies and more robust tracking of their postdocs. These large changes, unrelated to hiring or layoffs, sometimes masked population trends in the broader biological sciences postdoc population. We propose the adoption of a unified definition and titles for postdocs and the creation of an index to better assess biological sciences postdoc population trends. Abbreviations NSF National Science Foundation NCSES National Center for Science and Engineering Statistics GSS Survey of Graduate Students and Postdoctorates in Science and Engineering