The spec's say the total unadjusted error is 2 LSB. That means that if you want consistency, you have to (a) average and guess or (b) mask off the 2 lsb and use the remaining 6, which, if the noise is sufficient, may still not be consistent.

Unless power is dead-quiet, you'll always have to apply some form of "educated guess."

In most systems having a microcontroller, the switching noise is sufficient to make only the top 8-9 bits of a 16-bit converter valid. This one is an 8-bitter, and I'd not bet much on more than 6 bits even if the Vcc-to-GND noise is well under -72db. It's hard to imagine anything less noisy the the inside of a microcontroller with counters, serial ports, etc, and the faster it runs, the more energy there will be in the switching noise.

RE