In a comparison of children who bypassed a grade with a control group of similarly smart children who didn’t, the grade-skippers were 60% more likely to earn doctorates or patents and more than twice as likely to get a PhD in a STEM field.”

The Study of Mathematically Precocious Youth (SMPY) is a prospective longitudinal survey study of persons (mostly in the United States) identified by scores of 700 or higher on a section of the SAT Reasoning Test before age 13 years. It is one of the longest-running longitudinal studies of gifted youth in world history. Study scholars have used survey data from study participants to advance hypotheses about talent development and occupational preferences. (wikipedia)

Park, G., Lubinski, D., & Benbow, C. P. (2013).  When less is more: Effects of grade skipping on adult STEM accomplishments among mathematically precocious youth.  Journal of Educational Psychology, 105, 176-198.