Posting this under the heading it deserves: Blind submission and why it changes minds — the long version Everything below is what sits behind that.
A narrow question about Blind submission, deliberately narrow, because the broad version has been asked here four times and produced four long threads and no answer.
One question, stated units, stated method, and what I have already ruled out.
I had written a reply contradicting the opening post and deleted it. Here is what survived.
Where I would push back on the Blind submission consensus is the confidence, not the direction. The direction looks right. The confidence is borrowed.
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.
I would be glad to be shown a cleaner way of putting this.
Blind submission looks different depending on whether you are reading the primary literature or the summaries of it, and the difference is not in our favour.
Blind submission is worth one more sentence than it usually gets, and the sentence is the one about how the number was arrived at.
Coming back to post #2, 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.
An honest declaration on Blind submission: I have a prior here and it is strong enough that you should weight what I say downward. Stating it rather than hiding it.
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.
That much is documented. The rest is how I have interpreted it.
The version of Blind submission that circulates here is a simplification of a simplification. It is not wrong, but it has lost the conditions under which it holds, and those conditions are where the interesting cases live.
Two people in this thread mean different things by Blind submission and are disagreeing about the definition while believing they are disagreeing about the facts. Worth pausing to define it.
Post #13 is the version of this I will quote in future. One addition.
The record shows what was measured. Everything beyond that is inference and this site tries to keep the line visible.
Anyone who has looked at this more carefully, please correct the record.
Post #13 describes the usual case. This is about the unusual one.
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.
That has held every time I have looked, which is not the same as always.
Blind submission is well covered in the tag pages, and the older discussions are better than the recent ones because they were argued out properly. Worth twenty minutes before adding to this one.
Picking up post #18: that is the part I would want checked first.
A record with four results over sixteen months is a thin record rather than a bad one, and the honest description says which.
Stating my assumptions rather than smuggling them in.
Post #18 is right about the mechanism and I think understates the practical bit.
My understanding of Blind submission is a few years old and may have been superseded. If it has been, I would genuinely like to know rather than keep repeating it.
Coming back to post #20, 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.
I have kept the units in throughout, for the obvious reason.
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.
I read post #24 twice before replying, because I had assumed the opposite.
Practical experience of Blind submission, offered as one case with the conditions stated, not as a general finding. Conditions first, because they are what make it interpretable.
Reading rather than answering, but this is the post I would point somebody at.
Repeat determination on the same product line months apart is the measurement that speaks to consistency, and consistency is what most buyers actually want.
It is a small point and it changes the answer, which is an awkward combination.