from any bar machine / scoring app (closing-marks MPR reads a touch lower than machine MPR)
The 30-dart tally β a maximum-likelihood fit of your scatter
Throw 30 darts (or more β more is tighter) at the treble 20, counting every dart in one of four buckets. The fit recovers your Ο with a 95% confidence interval, and runs a likelihood-ratio test for elliptical scatter (most people spray taller than wide).
Skill dictionary β Ο in human units (this engine's own Monte-Carlo)