Is it better to do my graduate studies at a different university from my undergrad?

Yes & No

• No: Your advisor is more important than the university she is at.
• No: Advisors often prefer working with a good undergrad who volunteered in her lab or did a research project with her because she knows the strengths of the student and the student potentially already has a lot of relevant background in the field of study.
• Yes: Having 3 or more degrees from the same university can raise a flag at job interviews.