[31] See chapter 2 for a discussion of international higher education trends and chapter 4 for a discussion of trends in U.S. R&D.

[32] For details on survey and indicator construction, see Porter et al. (2005).

[33] For information on the validity and reliability testing the indicators have undergone, see Porter et al. (2001, 2005) and Roessner, Porter, and Xu (1992).