Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Distribution of studies (n = 450) by subject area. Some studies are included in more than one subject. The category other (n = 16) includes Chemical Engineering, Chemistry, Computer Science, Economics, Econometrics and Finance, Physics and Astronomy, Energy, Immunology, and Microbiology.
