#test-results 2024-06-25

selection bias

99.2 against a certificate of 96.8 is fine. the same supplier landing low four times in a row is a question, from memory

my read after three years of this: purity is mostly fine across the market and fill consistency is where suppliers differ

when did you buy it

sorry to jump in anyone had a result they think was a lab error rather than a bad vial

log the boring ones

what interests me is when the gap goes the same direction every time. once is noise, three times is a pattern, i could be wrong

do you test every order or sample it

a supplier disputing a result is rare here and it has never gone well for the supplier

i test roughly every tenth vial. it is a sampling strategy, not paranoia, ymmv

does a bad result on one lot condemn the whole supplier

the honest limits: hobby chain of custody is weak and any result here should be read with that in mind, i have it written down somewhere

the results in this channel skew because people test when they are suspicious. that is selection bias and it is real

coming back to this update from 16 months ago: retested the same supplier, result came back better, logged both