I’m studying for the CISSP exam. Inference and aggregation are means used to take low level or partial information and use that to derive higher level information. Inference requires deduction. The lower level information provides clues. Aggregation is a mathematical or mechanical process. Apply inference and aggregation to safe cracking (or lock picking). Using inference I can listen very closely to the safe and try to hear when the tumblers inside the locking mechanism move. Those tumblers moving are a lower level clue as one digit of a multiple digit combination. Using aggregation I start working on possible combinations and try each one. Perhaps the only lower level information required is how many numbers are in the combination.