Okay here is a couple of things.
Kinnem is correct it is an OML type situation. There are certain % awarded to certain aspects, such as, their cgpa, PFA, AFOQT and CoC's ranking. Plus going rated or not.
~ The cgpa has a twist to it. Tech majors are given an edge and because of that it is common for them to have a lower cgpa. 3.0/3.1. Non-tech majore @3.4 cgpa.
~ The CoC ranking is the biggest chunk.
~ If they fail the AFOQT it is going to be an issue. They may be selected to attend SFT if they failed it, but must pass it prior or get a waiver. AFOQT is like the ACT. They can only take it twice, and must be at least 180 days apart. The AFOQT is last test, not a superscore or best sitting. In other words it can be at a disadvantage to take it a second time since if they did better on the 1st, you are still stuck with the 2nd test scores.
~ They will be asked to sign paperwork whether they want to go rated or not.
~~ If they sign rated than they are required to apply for a rated board as a C300. They can't say yes they will go rated to get the slot and change their mind later....gaming the system. Basically, again this is like going tech. It is an edge to sign rated paperwork.
The selection board is national. It does not award a % to each college. Basically, they will say they Have @1900 slots. If 100% from that one school makes the cut and only 75% from another makes it so, than so be it. Some colleges statistically will have a historically a different higher or lower rate than others.
Scholarship are considered "masked" or "blind". This means the board has no clue which candidate is scholarship and which is not. However, impo the reason you see a large % of scholarship selected is because many of those cadets are also on merit at their colleges. Most college merit will require a 3.0+ to maintain the scholarship. My DS was both AFROTC and merit. His merit required a 3.2 gpa...note gpa, not cgpa. IOWS if for even 1 semester his gpa dropped under 3.2, but overall was 3.4 cgpa, he was put on probation by the school not AFROTC, since AFROTC scholarship min was 2.5.
My best advice is to talk to each unit and ask very pointed questions. What is the avg % selected for SFT? What is the avg cgpa for those selected? I would also have your child ask to meet cadets in their major that are POCs (C300s). Dets are different. They have different personalities.
As everyone has stated as a POC they will get a stipend. The only clarification I would state is that they will be paid on the 1st and the 15th, not the beginning and the end. Pay is done in the arrears. Thus, if they contract on the 5th, their 15th stipend will only be for the days between the 5th and the 15th, not the full stipend.
~ I would also not count on whatever stipend it is now. DS entered and it was 250/350/450/550. Due to sequestration they dropped the stipend. Nobody knows the future.
~ Same is true for selection rate. In the last 4 years it has jumped between 55% to 93%. It has a lot to do with the pool size which nobody can predict currently. The only thing that HQ AFROTC knows for sure when they contract as 100s (scholarship) is how many 100s contracted, but that is it. They cannot predict how many will stay as 200s. They cannot predict how many 250s will enter. Yet, they do know how many slots will be available for SFT. Thus, if in the end they have 2800 200/250/500s, and only 1900 slots than that % will be lower than if they have 2200 and need 2000.
Good luck. Hope that helps.