Discovered the difference between a candidate waitlisted before interview and another waitlisted after interview: This is from a 2006 Haas waitlist chat transcript:
"PeteJohnsonHAAS (Feb 15, 2006 10:08:04 AM)
Jstone, typically, we interview when we wish to gain more information about an applicant. If we interview someone prior to placing them on the waitlist, it means that we needed more information before making that decision. If we placed someone on the waitlist prior to an interview, it means that we felt that was the appropriate decision even before having the interview
JettPihakisHAAS (Feb 15, 2006 10:10:35 AM)
Toby, this is actually a bit complicated and a difficult question to answer briefly, but I will give it my best shot. We invite people to interview based on the quality of their written application. Those with the strongest applications get invites to interview. Those whose applications aren't quite as strong are waitlisted, which means that they are simply invited to interview a bit later in the process. Being waitlisted simply means that we have not made a final decision on your application, that's all."