Table 31. Median years to doctorate, by broad field of study: Selected years, 1991–2016
Field of study and time to degree 
1991 
1996 
2001 
2006 
2011 
2016 
All fields 






Since bachelor's 
10.5 
10.8 
10.2 
9.6 
9.1 
8.8 
Since starting graduate school 
8.7 
8.7 
8.3 
8.0 
7.7 
7.3 
Since starting doctoral program^{a} 
na 
na 
na 
na 
na 
5.7 
Life sciences^{b} 






Since bachelor's 
9.2 
9.6 
9.0 
8.6 
8.6 
8.2 
Since starting graduate school 
7.7 
7.9 
7.3 
7.0 
6.9 
6.7 
Since starting doctoral program^{a} 
na 
na 
na 
na 
na 
5.7 
Physical sciences and earth sciences 






Since bachelor's 
7.6 
8.0 
7.5 
7.4 
7.4 
6.9 
Since starting graduate school 
6.7 
6.8 
6.6 
6.5 
6.6 
6.1 
Since starting doctoral program^{a} 
na 
na 
na 
na 
na 
5.7 
Mathematics and computer sciences 






Since bachelor's 
8.6 
9.2 
8.5 
8.2 
7.9 
7.9 
Since starting graduate school 
7.2 
7.7 
7.2 
7.2 
6.9 
6.9 
Since starting doctoral program^{a} 
na 
na 
na 
na 
na 
5.7 
Psychology and social sciences 






Since bachelor's 
10.7 
10.3 
9.9 
9.8 
9.6 
9.5 
Since starting graduate school 
8.7 
8.2 
7.9 
8.0 
7.8 
7.9 
Since starting doctoral program^{a} 
na 
na 
na 
na 
na 
6.0 
Engineering 






Since bachelor's 
8.6 
9.0 
8.4 
8.1 
7.8 
7.3 
Since starting graduate school 
6.9 
7.2 
7.1 
7.0 
6.8 
6.5 
Since starting doctoral program^{a} 
na 
na 
na 
na 
na 
5.3 
Education 






Since bachelor's 
18.5 
20.3 
19.0 
16.7 
15.0 
15.0 
Since starting graduate school 
15.2 
15.9 
13.9 
12.7 
11.7 
11.7 
Since starting doctoral program^{a} 
na 
na 
na 
na 
na 
6.0 
Humanities and arts 






Since bachelor's 
12.6 
12.0 
11.6 
11.6 
11.2 
11.0 
Since starting graduate school 
10.7 
9.9 
9.7 
9.7 
9.3 
9.3 
Since starting doctoral program^{a} 
na 
na 
na 
na 
na 
7.0 
Other^{c} 






Since bachelor's 
13.4 
13.5 
13.6 
12.3 
12.0 
11.2 
Since starting graduate school 
10.7 
10.2 
10.7 
9.8 
9.3 
9.0 
Since starting doctoral program^{a} 
na 
na 
na 
na 
na 
5.3 