Acknowledgments This publication was developed by R. Keith Wilkinson, Project Officer, Science and Engineering Personnel Program (PER) of the National Science Foundation's Division of Science Resources Studies (SRS). Technical assistance for this project was provided by Linda Hardy of SRS and Geraldine Mooney and Brenda Cox of Mathematica Policy Research under contract No. SRS-90-14942. The project was developed under the supervision of Carlos Kruytbosch, Program Director, PER, with guidance and review provided by the SRS Director, Kenneth M. Brown. SRS is grateful to Susan Mitchell, Prudy Brown, Dan Pasquini, and Ramal Moonsinghe from the National Research Council for having conducted the survey under contract No. SRS-93-14268.