The data for MSAR comes from two different places
1) Applications submitted, verified, and residency (IS/OOS/Intl) come from aggregate AMCAS data. Please note that residency here is simply what applicant states as address on the AMCAS. It is NOT determining residency as each school may use in their admissions data and subsequent data.
2) all other data comes from each school entering numbers into end of cycle AMCAS reports. By this point most should be automated but still relies on data being entered correctly across systems, which can have human error, process error, or coding error
3) about 1% of matriculants per year report they did not attend any interview. These could come from linked UG/PB/SMP programs as well as other reasons