I applied online. The process took 4 weeks. I interviewed at Purdue University (West Lafayette, IN) in Mar 2013
Interview
I spent the better part of a day at the school after I had applied and received an acceptance letter and offer. A herd of current graduate students took me to lunch and were friendly, welcoming, honest, and helpful. The graduate coordinator was also a big sell, could answer any question imaginable and was super-friendly about it all.
Get a call from an PI, asked about my past research experience, course works and my research interest if I joined their lab. Also talked about their own experience as a graduate student and junior PI. Overall smooth and positive experience.
I applied through university. I interviewed at Purdue University (West Lafayette, IN) in Jan 2017
Interview
Interview process was smooth and friendly. I interviewed with several professors and was shown Purdue on-campus and off-campus research locations. My interview clothes did not arrive with my flight, but my interviewers were very gracious and understanding.