one data point
#test-results 2024-09-05
Thursday35 messages7 participantstimes are UTC
Highlights from this day
- HPLC_Hank — if the vial has been through a bad transit you are testing the transit as much as the supplier 12:14
- HPLC_Hank — quantity testing is usually a separate line item and it is the one worth paying for 12:29
- HPLC_Hank — i told HJ about a result they would not have liked and they did not argue. credit where it is due 12:30
- HPLC_Hank — do you test every order or sample it 13:43
- deadspace — genuine question does anyone log the negative results, the boring ones 15:27
anyone tested the same lot twice at different labs
post the lot, the purchase month, the lab, the number, and what you were expecting. that makes it useful later
selection bias
if you are testing to settle an argument you will not settle it with n of 1
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how much does sample handling on my end affect the number
if the vial has been through a bad transit you are testing the transit as much as the supplier
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do the results in this channel skew because people test when suspicious
quantity testing is usually a separate line item and it is the one worth paying for
| Evidence | Counts? |
|---|---|
| Independent report, lot you bought, lot number legible | yes |
| Independent report, no lot number | no |
| Supplier certificate only | no |
| Screenshot of a report | no |
| Blinded pooled submission | yes, for the pool |
| A friend who said it was fine | no |
i told HJ about a result they would not have liked and they did not argue. credit where it is due
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coming back to this sample handling on your end absolutely affects it. draw cleanly, ship fast, do not let it sit warm
log the boring ones
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how do you separate batch variance from supplier variance
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is a purity-only test worth the money if underfill is the common failure
the honest limits: hobby chain of custody is weak and any result here should be read with that in mind
underfill is more common than impurity. if you only test purity you are testing the less likely failure
do you test every order or sample it
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quick one whats the worst result anyone has logged and what happened next
thats within range
log the lot number
test it again
nice result
whats the lot
log the boring results too. a channel that only records failures produces a false picture, ymmv
a point or two between the certificate and an independent result is inside what two labs disagree by
coming back after 13 months with a follow up result, where do i put it
right so the results in this channel skew because people test when they are suspicious. that is selection bias and it is real
the widest spread in my data is about 2.6 percentage points across five lots from one supplier
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my sheet has 3 lots from WXT with a spread under a point, which is tight
thats not great
assay under label with good purity means you got less of the right thing. that is a fill problem, not a synthesis problem
unrelated but what interests me is when the gap goes the same direction every time. once is noise, three times is a pattern
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posting my PeptideMeter result on lot A-2601, what do people make of it
genuine question does anyone log the negative results, the boring ones
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when did you buy it