The rotation two-pass reverts to the header geometry when the refined pass
looks worse. It decided that on the search merge's pooled, uncut,
pre-correction P1 CC1/2 - a number that reads 0.13 on a crystal whose data
merge at 0.995, and that moves 0.93 to 0.76 between two runs whose merged
data agree to 0.7% of R_meas. Two crystals were sent back to a geometry that
ships 22% fewer reflections than the one they refused.
Compare instead what each pass MEASURED: reflections merged at I/sigma >= 2.
Against an external arbiter that objective agrees with which geometry is the
more accurate one on 23 of 27 arm-dataset pairs, where self-consistency
measures agree on 13 of 27. Count it on both sides over the centring-allowed
reflections, so a pass that finds a centring the other did not is not judged
on the extinguished half its P1 merge holds as noise (two crystals compared
merges holding 2.0x the reflections of the other), and ask the axial-row arm
only where the two passes are in the same setting, which is the only case
where the two counts are counts of the same reflections.
The bar is a decisive loss rather than a bare inequality: the two passes
never integrate the same way - the canonical pass integrates at the measured
spot width and predicts with the pre-pass's smoothed mosaicity - so a
difference that small is not evidence about the geometry either way.
leonarski_f
ea37056fe9
