Probably not what you want to hear.
Remove the dogs, install a new out of the box yellow / non-safety chain and retest. Guessing the variation will decrease dramatically. Having been to many GTG in the past, the number of people observed that think slamming the dogs into the log and lifting with their legs is proper sawing technique is alarming. Also explains why so many people think they need a 90cc saw.
As previously stated saw, bar length, chain mfg and type, and a pic of the chain would all be useful data.
Not discussed, but another factor to look at is the chain tension. Either too loose, or too tight can cause issues pulling a chip in the kerf.
Take Care