One morning the north part of the LTMA went into chaos with a squawking aircraft going through the middle at (apparently) FL70. We later learned that it was a small aircraft at around 1500 ft.
Interesting to note that the one anecdotal example of an incorrect Mode C return that we have is a discrepancy of more than 5000 ft. Under a RAS, minimum separation of only 3000 ft is provided against unverified Mode C.
Is there any reason to believe that discrepancies of say 300 to 3000 ft are more likely than completely random returns?