回复：呵呵，还在扯小留的话题啊。想请坛子上的高人们介绍一下

Double D saves tuition for medical school but costs you at least 3 more years.  Some may say double D is tougher to get in but it depends.  Sometimes MD is tougher to get in than double D.  Also, many people don't want to spend 3 additional years for tuition benefit since you can make up at least part of the difference financially in saved 3 years.  But if you objective is research and want to be professor in academic field then double D helps.  MDs who want to do research usually either get a PhD in fundamental research areas or a doctor or master in public health like statistics or epidemiology. The former will do bench work in labs and the latter will do population medicine using their statistics and epidemiology knowledge.  But a lot of MDs who don't have either phD or doctor/master in public health but do great research since if they are great in clinics and can hire people with the knowledge.  A PhD degree will help you understand more basic sciences but many PhDs also tend to focus too much on details and lose the bigger pictures.  I guess it's a trade off/balance and all depends on personal choices and personality.