Students pursuing a Ph.D. in a program other than Economics may apply for the Ph.D. Minor in Economics. Ph.D. students cannot pursue a minor in their own program.
The minimum University requirement for a Ph.D. minor is 20 units of coursework at the graduate level (courses numbered 200 and above) at Stanford. Units taken for the minor can be counted as part of the overall requirement for the Ph.D. of 135 units done at Stanford. Courses used for a minor may not be used also to meet the requirements for a master's degree.
To be recommended for the Ph.D. degree with Economics as a minor subject, a student must qualify in three fields of economics, at least one of which must be in the core economics sequence (microeconomics, macroeconomics, or econometrics). The standard of achievement in these fields is the same for minor as for major candidates - typically two courses per field (often with a paper requirement), and passing the exams in the core field(s). A list of fields, field requirements and the courses which satisfy the field requirements can be found here: Graduate Degree Program Requirements.
A Ph.D. minor form outlining the program of study must be approved by the major and minor departments. The form can be found here: http://studentaffairs.stanford.edu/sites/default/files/registrar/files/app_phd_minor.pdf