Graduate science education in the United States
Course of study
Depending on the specific field of study, completion of a PhD program usually takes four to eight years of study after the Bachelor's Degree; those students who begin a PhD program with a master's degree may complete their PhD degree a year or two sooner. As PhD programs typically lack the formal structure of undergraduate education or related professional degree education (JD, MD, DVM, MBA, etc.), there are significant individual differences in the time taken to complete the degree. Many U.S. universities have set a ten-year limit for students in PhD programs, or refuse to consider graduate credit older than ten years as counting towards a PhD degree. Similarly, students may be required to re-take the comprehensive exam if they do not defend their dissertations within five years after submitting it to their self-chosen dissertation advisors.[citation needed] Overall, 57% of students who begin a PhD program in the US will complete their degree within ten years, approximately 30% will drop out or be dismissed, and the remaining 13% of students will continue on past ten years.
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