I spent 2 years at BCG after graduating from Duke, and was very active in the recruiting process (e.g. screening candidates and conducting on-campus interviews) so I wanted to add some observations:
In terms of determining the interview list, the MBB firms use both a quantitative resume scoring system combined with qualitative observations from all of the interactions with candidates.
On the quant side, you are assigned different point values for the caliber of your undergrad and MBA programs (or other grad degrees), your bschool GPA, GMAT, prestige of your previous employers, demonstrated impact /advancement professionally, and leadership experience. Based on the total score across all these dimensions you are categorized as either being a likely or not likely interview candidate. The resume scoring often influences who gets invited to certain "high-priority" events like firm dinners, etc.
On the qualitative side, the firms keep detailed notes on all their interactions with you whether that's at their company presentation, cocktail events, or mock interviews. The are trying to evaluate your communication ability (e.g. can you speak well?) as well as how well you'd fit in as a member of the team or in front of clients (are you awkward? are you arrogant?).
In forming the interview list they take into account all these factors.
Additionally, the interview lists are shaped by both the on-campus "specialists" as well as the specific offices. Behind the scenes, offices have certain numbers of interview "slots" for each school, so there is a lot of give-and-take behind the scenes. (For example, the Boston office might be really high on a candidate so they push hard to proceed with the interview, even if the school-specific recruiting team was luke-warm on the candidate).
Once you get to the interview stages, everyone has a more or less equal chance regardless of whether you were at the top of the list, or the last one who made the closed list. It all comes down to executing during the interviews.
For those of you who are relatively weak along one of the quant dimensions they evaluate you on, take heart. I went to a smaller regional undergrad (so I was a lot lower on that dimension than my Ivy-League peers), but was able to overcome that by virtue of a strong GMAT, networking, packaging my resume effectively, and then performing strongly in my mock cases; and then ultimately the interviews themselves.
Please check out our new thread "ask Beyond Case Prep - advice from MBB alumni" and feel free to ask any consulting related questions. ask-beyondcaseprep-consulting-information-from-mbb-alumni-156850.html