@ghjkI'm sorry to hear about Columbia IEOR...
I was very fortunate to have been contacted by Columbia IEOR towards the end of last week. I had my interview this morning, and it was relatively short at around 15 minutes. We chatted generally about my background, including projects and any publications, as well as research interests and goals going forward. The professor, who I assume is a member of the admissions committee, also asked me which faculty members in particular I'm interested in working with.
I applied to PhD programs in both operations research and statistics. For OR programs, I applied to Columbia, Cornell, Princeton and Stanford. I'm a domestic applicant currently doing a Statistics MS at a top program. My research interests are spread out across applied probability, finance and statistical theory.
It would be nice to hear about others' interview experiences. The interviewer told me I should hear back with the final admissions decision within about two weeks.
Best of luck to everyone!