"What percentage of your applicants will be invited to interview?" "Of the applicants who interview, what percentage will be admitted?" As the Round 1 applications continue, I've heard a lot of speculation about the process.
Contrary to popular belief, there is no fixed percentage of applicants who are interviewed, and chances of admission for those who do interview are based on the strength of the entire application package and the interview. In the past few years, between 25% and 30% of all applicants have been selected to interview—but keep in mind that this percentage has varied each year. It's simply a reflection of the strength of the candidates in a specific round.
Although it's a positive sign to be invited to interview, it doesn't mean you'll get an offer—but it does mean that the Admissions Committee saw enough strengths in your application to be seriously considering your candidacy, so it's always a good sign!
If you are invited to interview, be sure to listen to the Interview tips podcast, which you can find at http://www.haas.berkeley.edu/haas/podcast/audio/haas_mba_interview_tips1.mp3.