@mathteacher Oh yeah when I performed adjustments as a USMC geodetic work. I always did 68% first. Saved those results off to the side. Then same raw data non adjusted processed at 95% and 99%. We had a macro written that would identify the deltas and or differences in angular distance vectors heights etc. If all three resulting positions from each fell within a certain range we knew we had no blunders and probably had a good data set. Now our field procedures were very rigid vs what we do on this side of the house and for obvious reasons. On chi I don’t hold it very high honestly it’s a quick indicator of my estimates and our that I probably have missed a blunder somewhere. So I truly don’t get wrapped around the horn on its pass fail. Tau I look at and any azimuth rotation and the semi major and minor along with direction and size. The amount of movement in the adjusted end results vs raw observation results. The ppm of each to each other. I have forgotten so much in how all we did things back then. All the covariance information and how I did apply that etc. I need to pick up a book and relearn all that again but we are not building watches what I am doing now so I have learned to relax a bit more well trying to. lol. My brain still kicks in when I see sloppy work