We thank Aaron Vaught for compiling institutional data, R. Joseph Waddington for suggestions on data analysis, and Margaret DiGirolamo for help with organizing data. We also thank the research advisors and their laboratory personnel for conducting SRE sections. This work was supported by an HHMI Sustaining Excellence-2014 grant (#52008116) awarded to the UK (V.M.C., principal investigator). The content and views expressed in this paper are the sole responsibility of the authors and do not necessarily represent the official views of the granting agency or the UK. This study was reviewed and approved by the UK Institutional Review Board (protocol 15-1089-P4S).