Table 4-4
Total time to doctorate, registered time to doctorate, and time from first postbaccalaureate attendance at Ph.D.-granting institution to doctorate, by major field: 1995–99
(Median years)
 
Field TTD RTD PTD
All fields 10.6 7.3 6.0
Science and engineering 9.0 7.0 6.0
Agricultural sciences 11.1 6.8 5.0
Biological sciences 8.4 6.9 6.0
Earth, atmospheric, and ocean sciences 10.8 7.6 6.0
Mathematics and computer sciences 9.0 7.0 6.0
Mathematics 8.3 6.9 5.0
Computer sciences 10.0 7.4 6.0
Physical sciences 7.4 6.4 6.0
Chemistry 7.0 6.0 5.0
Physics and astronomy 7.8 6.9 6.0
Psychology 9.3 7.2 6.0
Social sciences 11.0 8.0 6.0
Engineering 9.0 6.5 5.0
Non-science and engineering 15.1 8.3 6.0
Education 20.0 8.3 6.0
Health sciences 14.2 7.8 6.0
Humanities 11.8 8.6 7.0
Professional fields/other 13.6 7.8 6.0
 
NOTES: TTD is total time to doctorate, based on years and months to degree. RTD is registered time to doctorate, based on years and months to degree. PTD is postbaccalaureate time to doctorate, based on whole years from year of graduate-school entry.
 
SOURCE: NSF/NIH/USED/NEH/USDA/NASA, Survey of Earned Doctorates and Doctorate Records File.
 
U.S. Doctorates in the 20th Century