selection bias
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#test-results 2025-05-12
Monday21 messages7 participantstimes are UTC
Highlights from this day
- plateau_pen — i told GGPeps about a result they would not have liked and they did not argue. credit where it is due 11:12
- ms_ms_mira — one bad test does not condemn a supplier. one good test does not clear one. both halves get ignored equally, your mileage will differ 11:15
- ms_ms_mira — log the boring results too. a channel that only records failures produces a false picture 12:41
- salt_bridge — the widest spread in my data is about 2.6 percentage points across five lots from one supplier 14:22
for the archive what interests me is when the gap goes the same direction every time. once is noise, three times is a pattern
log the lot number
how much does sample handling on my end affect the number
[edited]a point or two between the certificate and an independent result is inside what two labs disagree by
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unrelated but the honest limits: hobby chain of custody is weak and any result here should be read with that in mind
quick one if you are testing to settle an argument you will not settle it with n of 1
certificate said 99 and the independent came back 99.4, is that a problem
i told GGPeps about a result they would not have liked and they did not argue. credit where it is due
my read after three years of this: purity is mostly fine across the market and fill consistency is where suppliers differ, not advice obviously
one bad test does not condemn a supplier. one good test does not clear one. both halves get ignored equally, your mileage will differ
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the results in this channel skew because people test when they are suspicious. that is selection bias and it is real
when did you buy it
log the boring results too. a channel that only records failures produces a false picture
lot bought purity assay/label
A-2418 2025-03 99.1% 9.6 / 10mg
A-2601 2025-08 98.7% 9.8 / 10mg
B-0114 2026-01 99.3% 9.4 / 10mg
B-0329 2026-04 98.9% 9.9 / 10mgfor the archive does a bad result on one lot condemn the whole supplier
whats the lot
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does anyone log the negative results, the boring ones
slightly off topic but my result contradicts the supplier certificate, do i tell them
the widest spread in my data is about 2.6 percentage points across five lots from one supplier
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posting my VendorInvestigate result on lot E-2205, what do people make of it
anyone had a result they think was a lab error rather than a bad vial