Does Duke have higher standards for more competitive regions?

No, that is not how it works…Duke tries to offer everybody an interview and pairs up a volunteer interviewer with an applicant within a region without regard to application merit. Duke also does not have any quotas or differing standards for a particular region – they simply want the best class possible. And to your last point, very strong applicants should NOT decline an interview – that does not look good no matter how strong the application is.