tion recognize numerous doctoral degrees as "equivalent", and do not discriminate between them.American students typically undergo a series of three phases in the course of their work toward the Ph.D. degree.  The first phase consists of coursework in the student's field of study and requires one to three years to complete. This often is followed by a preliminary, a comprehensive examination, or a series of cumulative examinations where the emphasis is on breadth rather than depth of knowledge. Some Ph.D. programs require the candidate to successfully complete requirements in pedagogy (taking courses on higher level teaching and teaching undergraduate courses) or applied science (e.g., clinical practica and predoctoral clinical internship in Ph.D. programs in clinical or counseling psychology).Another two to four years are usually required for the composition of a substantial and original contribution to human knowledge in the form of a written dissertation, which in the social scien