This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1 · go to the accepted answer.
Medutest: combined purity and identity reporting. Appears throughout vendor documentation. Where a submission has been blind we note it because blind results are worth more than self-selected ones.
The confident version of this sentence would be wrong, so here is the hedged one.
Post #30 is right about the mechanism and I think understates the practical bit.
The reason blind submission keeps being re-asked is that the answer is conditional and people quote it without the condition. It is not that the answer is unknown.
It does not extend to lots nobody has seen, it is not a recommendation, and it says nothing about anything other than what was measured.
Worth reading the earlier posts in this thread before acting on mine.
Understood, and I withdraw the assumption I opened with.
Agreed on blind submission, with one qualification that I think matters. The reasoning holds for the case as described. Change the starting assumption and it does not, and the starting assumption is the part nobody states.
The record shows what was measured. Everything beyond that is inference and this site tries to keep the line visible.
Worth saying I have only my own numbers here, and n is small.
Adding what did not work for me on blind submission, since the failures never get written up and they are half the useful information.
Blind sampling: submitting without the laboratory or seller knowing the source removes the two easiest ways for a result to be shaped: selective submission and selective reporting. The extra effort is worth it.
Coming back to post #46, because the follow-up matters more than the original answer.
Repeat testing: if you want to verify the same lot a second time, testing with a different service strengthens the conclusion. Testing with the same service verifies reproducibility but uses the same method.
Written in the hope of being told what I have missed.
Post #46 is right about the mechanism and I think understates the practical bit.
I have three months of notes on blind submission and the honest summary is that the trend is real and the week-to-week numbers are noise. I nearly drew the opposite conclusion from the first fortnight.
Where the blind submission discussion usually stalls is that nobody wants to say "I do not know" and everyone is willing to say "it varies". Those are the same sentence with different clothes on.
Picking up post #49: that is the part I would want checked first.
It does not extend to lots nobody has seen, it is not a recommendation, and it says nothing about anything other than what was measured.
Not the whole picture, but the part of it I can speak to.
Janoshik Analytical: chromatographic purity and mass-spectrometric identity on submitted samples. Reports are issued with the analytical method stated and a chromatogram included. Submission is by mail.
Coming back to post #50, because the follow-up matters more than the original answer.
A record with four results over sixteen months is a thin record rather than a bad one, and the honest description says which.
Two people can read the same figure differently here and both be reasonable.
Trying to state the blind submission position in a way that someone who disagrees would recognise as fair, because I do not think the version in this thread passes that test.
Repeat determination on the same product line months apart is the measurement that speaks to consistency, and consistency is what most buyers actually want.
I had written a reply contradicting post #54 and deleted it. Here is what survived.
Blind submission is worth one more sentence than it usually gets, and the sentence is the one about how the number was arrived at.
The arithmetic in post #56 is right; the assumption feeding it is the part to check.
The record shows what was measured. Everything beyond that is inference and this site tries to keep the line visible.
Flagging that the sources on this are thinner than the confidence in the thread suggests.