Originally Posted by
tenrec
If that's the case, I wonder if the accuracy would vary on different days as the barometric pressure varies. I also wonder if any apps or devices use topographical maps along with GPS data -- I expect that would be significantly more accurate.
It’s probably a combination of factors. Errors aren’t additive but generally multiplicative. Daily variances in satellite communication, refresh rate, where the measurement is made, etc can lead to errors propagating more in one measurement than another. For example, the 886 foot measurement could have been a case of the GPS missing measuring at the high points. The 1400 foot measurement may over poled the satellite at the high points more.
All that said, it’s not the big of a deal. Since you have multiple points of data, average, do a standard deviation, and accept the average.