[2] Physical sciences include earth, atmospheric, and ocean sciences.

[3] Research institutions are classified according to the 1994 Carnegie classification. See Science and Engineering Indicators 2006 (NSB 2006) for definitions of the various classification categories.

[4] Financial aid is calculated for all full-time students, both in state and out of state, so net price may be underestimated.

[5] For information on debt levels of clinical versus nonclinical psychology doctorates in 1993–96, see "Psychology Doctorate Recipients: How Much Financial Debt at Graduation?" (NSF 00-321) at