[Discussion] the below spec advice in here is 2 years out of date
the below spec advice in here is 2 years out of date. I have gone back and forth on this for months.
The numbers the title promised, since a headline without them is worthless: 2 years. Everything below is context for those.
The template is vendor, compound, batch, service, claim, result, and who paid. Every one of those fields exists because a result missing it has been argued about here before.
Inter-lab variance on this assay runs roughly a point either way, driven mostly by gradient and integration. Two results inside that band agree; they do not disagree quietly.
Sceptical readings welcome. The confident ones are the ones I distrust.
best — the order this archive was captured in
Merged with the other thread on the same batch so the results sit together.
Did the vial lot match the paperwork lot?
Disagree that this is a discrepancy. 98.1% against a claimed 97.5% is inside ordinary inter-lab variance in either direction.
if you are going to test, test the thing you actually received
Yes. Two services on the same batch is the strongest thing an individual member can produce, and it is not expensive.
This. The trend across separate lots is the number that tells you about a process rather than a vial.
results without method are gossip with decimals
[deleted]
Batch number and date of analysis?
Area percent or net peptide content?
Correcting myself: I quoted net peptide content against somebody else’s area percent. Not a comparison.
If the report gives a mass spectrum as well as UV purity, say so. Identity and relative quantity are separate claims and the log tracks both.
net peptide content if the report gives it, and say which you are quoting
vendor, compound, batch, service, result — that is the template
the log is cumulative, that is the whole value of it
Careful with the trend claim. Four results over two years is a very sparse series to draw a line through.
Tested three lots over a year rather than three vials from one lot. Cost the same and told me something completely different.
Push back: three tests on one lot is one lot. It tells you about that lot and almost nothing about the next one.
date of analysis matters as much as the number
Agreed on quoting the claim alongside the result. Half the arguments here are two people comparing to different reference numbers.
Small fix — same supplier, different lot. The two rows in the log are not the same batch.
How to build a series that means something, if you are going to spend money on testing anyway.
Three tests on one lot tells you about your measurement. Three tests on three lots, spread over a year, tells you about a process. The second is the one worth paying for and it costs the same.
Buy small, keep the batch numbers, send one vial per lot, and post each one with the claim next to it. After four or five you have something no individual review can give you: a band, a direction and a date range. That is what the source pages are made of.
Split one vial between Medutest and PeptideMeter. The two numbers were within half a point of each other and I stopped worrying about which lab to trust.
A series across separate lots estimates a process. Repeat tests on one lot estimate the measurement. Both are useful and they answer different questions.
Date of analysis anchors the result to a manufacturing period. A two-year-old result is evidence about two years ago and should be read that way.
three lots beats three tests on one lot
split a vial across two services once and you will never argue about ground truth again
Area percent and net peptide content are different measurements and most reports give one. Quote which, or the comparison downstream is meaningless.
Chain of custody is why member-funded testing is worth more than a supplied certificate: the vial tested is the vial that arrived at a member’s door.
That reading assumes area percent and net peptide content are the same number. They are not, and the report says which it is.
- 1Merged with the other thread on the same batch so the results sit together.11 comments in this branch · started by u/peptidemeter_pat
- 2A series across separate lots estimates a process. Repeat tests on one lot…7 comments in this branch · started by u/phase_two_pete