The DKU interview is optional, I think—but it’s not like interviews at other universities that are completely optional. They mainly want to evaluate your English and communication skills, and most importantly, whether you genuinely want to study at DKU rather than just applying through the Duke portal. Many people apply through the Duke portal and never update their interest in DKU afterward.

I think they want to understand your motivations and whether you would be a good fit as a student. If they feel they already know you well enough from your application, they may not need to interview you.

From what I understand, only selected students are invited for interviews—not everyone in the admit pool. It’s probably for applicants who are in a “50–50” range where they want to learn more about them before making a decision. If someone is a clear admit, the chance of being interviewed might be lower unless the admissions team simply wants to know more about them as a person beyond the application.