For all the applicants and parents of applicants to USC this year, it may be tempting to ask this question. But the truth is, of course, none of us knows the minds and hearts of each individual admissions rep, nor the exact make-up of a year's admitted class as it's being composed. So while one year, a needed tuba player may be golden, another year there may be wayyy too many tuba players. This won't likely ding the tuba player, mind you, but it is less likely to be a tip into the admitted pool for an otherwise on-the-cusp applicant. And so on.
USC's admissions are holistic, which means the committee will look at all aspects of the application, paying particular attention to essays, LoRs, and activities and accomplishments outside the classroom as they look to build a class that fits the institution's needs. That includes their need for diversity, geographic breadth, top talent for the arts majors, athletes, innovators, and leaders. However, it can be most instructive to really study the USC Freshman profile for the current year (2013 admits) to see the trend in objective criteria: gpa and test scores. You'll find the most recent year here: http://www.usc.edu/admission/undergraduate/apply/documents/FreshmanProfile2013FINAL.pdf
So how to interpret this data? First, the most important category to check is ADMITTED STUDENTS. This is the group you are attempting to join.
Top of the Heap Numbers: Those applicants who fall in the top 25% of ADMITTED students (both SAT + gpa unweighted), have the highest likelihood of being admitted this year. Not all will be, of course, so it's never a given when a school admits less than 20% of applicants. But those students would seem most likely. If these sorts of top academic students don't take their app seriously, dash off sloppy essays, make careless mistakes on the app, goof off on the short answers, use their Stanford essay and forget to swap out USC for Stanford (that sort of thing), or give off a whiff that they are collecting trophy admissions, but really really expect to go to another college, the adcom may see through their app and deny. It has happened. Many times. OTOH, if a stellar candidate takes the USC app seriously, writes excellent essays, and connects to the School they are applying for, by doing research, visiting, or in other ways shows how well they would fit into USC, and show passion and leadership in their major field, the chances are good this above-top-25% score/gpa applicant may be invited to interview for one of USC's top scholarships. In these cases, the invitations are awarded by each individual School, so achievements beyond the normal great student type of activities will help.
Top of One Heap: A top applicant with slightly mismatched scores/gpa--for instance, above top 25% SAT or ACT score, but a gpa that falls at about the middle of the 25-75% unweighted range (or the reverse), is still a serious candidate and should feel hopeful for a good outcome. In these cases, the supplemental material will certainly add to the decision. At USC, one's major will matter, and an applicant with particular accomplishments, awards, honors and/or special distinction in his/her field can definitely make a difference. Having an unusual life story, overcoming extreme adversity, and other hooks also come into play. In some cases, strong hooks will pull this type of applicant up into consideration for one of the top merit scholarships as well. Make sure to apply by the first deadline!
National Merit Scholars: The great news is, USC is the highest ranked university that offers guaranteed 1/2 tuition scholarships simply by scoring well on one test, on one day junior year. Congratulations to these students!! The not-so-great news is: NMF is not a guarantee of being ADMITTED to USC. There have been bitterly disappointed applicants in the past, who mis-read the language on USC's website, believing they were automatically admitted. No. But if your UW gpa and other criteria are good, you have an excellent chance of admissions.
Right in the Middle: Applicants who fall near the average GPA (currently 3.83 UW) and near the middle SAT (50% mark is not spelled out, but you can make a good guess by looking at the 25-75% range: ACT: ~32 SAT: ~2140) of Admitted Students have a good chance of admission. But there are many many applicants in this range and the competition keeps getting more intense. This might be considered a match school, but to be realistic, it's probably 60/40. Of course, this student would be a great asset to USC, but there are limited spots. Keep working on that supplement.
Hope for those in the lower quadrant: USC offers many students spots who fall below these numbers. After all, 25% of offers of admission (last year that was about 750 big envelopes) go to those whose scores or gpas are in the lowest quartile of scores. Who gets these spots? Most likely, the students with extraordinary talents or other life experiences that USC wants. This may include extraordinary individuals from households with economic challenges, serious adversity, or from countries/cultures with less advanced prep schools. In addition, USC has excellent talent-based Arts Schools (USCs Arts Schools (Architecture, Cinematic Arts, Dramatic Arts, Roski School of Fine Arts, Thornton School of Music) who value talent and potential as well as academic strength These applicants are judged on extra material, whether that means in-person auditions, creative supplements, and/or art portfolios. The same is true for gifted athletes who are recruited for one of USC's many Division I teams. There is no published information on how heavily talent/potential will count towards admission decisions. But all decisions must be approved for academic worthiness.
Help or No Help:
When looking over these published numbers, please do not forget that USC knows almost all of the sending high schools around the globe. They know schools with grade deflation as well as those with grade inflation. They know which students are taking the most rigorous schedule available, and those who do not. They definitely factor that information into their evaluations. Look at your own school's naviance and compare to the USC Freshman Profile. If students with slightly lower gpas seem to be admitted regularly, it is a good sign that your school is well regarded, despite school-wide grade deflation.
Best of luck to all applicants in this year's cycle.