Cross-section

VIP by laboratory

The same compound measured by different laboratories on different gradients. Where the medians differ, the question is whether the material differed or the method did — and for VIP, with a class minimum gradient of 15 min, the method is a live explanation.

12 recordsmedian 97.56 %spec 97.5 %

Laboratory	Reports	Gradient	MS resolution	Median purity %	Published bias (pp)	Bias-adjusted	Method suitability
Janoshik	5 n=5	30min	High	97.43	+0.00	97.43	ADEQUATE
Medutest	2 n=2	25min	Unit	99.28, 97.62	+0.08	—	ADEQUATE
VendorInvestigate	2 n=2	32min	High	96.37, 97.39	-0.11	—	ADEQUATE
PeptideMeter	1 n=1	28min	High	98.95	-0.05	—	ADEQUATE
Nordanalyt	1 n=1	35min	High	97.61	+0.02	—	ADEQUATE
Kestrel	1 n=1	15min	Unit	97.70	+0.24	—	ADEQUATE

Figure. VIP purity by contributing laboratory. Any offset between rows has two possible sources — a real difference in the material each laboratory happened to receive, and the laboratory's own bias — and this figure cannot separate them. The paired analysis that can is on inter-lab agreement.