
OPUSS, overly optimistic statistics?
I’ve seen comments that the OPUSS “horizontal accuracy” numbers were optimistic. I plotted several runs and Wow! are they ever. I would expect the ultrarapid, rapid, and precise reports to get progressively tighter, and most (95% ?) of the time fall within the
prior report 95% confidence region.I can calculate from the covariance matrix to approximately what the report gives as “horizontal accuracy” or more detailed, the 95% ellipse. This is not as correct as the method Loyal posted in a prior thread, but hoped the report’s covariance matrix would mostly reflect similar results except for not allowing std error for the CORS stations.
What I find is that the positions rarely fall within the prior report confidence region as calculated from the covariance matrix. And it’s not unusual for two sessions on the same spot to not even have their 95% regions overlapping.
Is “horizontal accuracy” number leaving out any uncertainty in the orbits/satellite clock, and maybe an inadequate allowance for multipath?
Do other people (with more modern equipment) see this effect?
———————
The 95% ellipses would tightly enclose the diamonds in these plots, which were easier to draw in Excel than ellipses. Despite the varying scales, all have 1 cm tick marks.
Log in to reply.