The 6-sigma outlier band was symmetric in I about the reflection's median,
while the error model's systematic term b*<I> is a multiplicative error
(absorption, illuminated volume, a scale that is off), as likely a factor 1/f
as f. With b of a few percent the two agree; with a large b the linear band
reaches far below the median and only a little above it. On a strongly
absorbing cubic crystal (internal b = 0.34) 96% of the 828 rejected fulls read
2-7x their median in well-illuminated frames - the least absorbed, nearest the
true intensity - and almost none read low.
The b part of the band is now exp(+-n*b) about the expected intensity, the
counting part stays linear (OutlierBand.h, one formula for the host loop and
the device kernel; the two exp constants are taken once on the host). To
first order in n*b it is the old band.
That set's SHELXL R1 0.116 -> 0.103 (--reject-outliers 12 / 20 on the old
band: 0.107 / 0.101; no rejection at all: 0.31).
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01K5K8jvPPbmCrbqnWkddTuB
leonarski_fandClaude Opus 5.5
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