Submitting a sample: the process end to end posts 91–115
This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.
Worth separating submitting a sample as a question about the compound from submitting a sample as a question about the documentation. They get answered by different people and only one of them is answerable here.
On post #91 — agreed on the reasoning, with one qualification.
Where I have landed on submitting a sample, having got it wrong once in public: the direction is clear, the magnitude is not, and anyone quoting a precise magnitude has borrowed it from somewhere that did not measure it.
Picking up post #91: that is the part I would want checked first.
Repeat determination on the same product line months apart is the measurement that speaks to consistency, and consistency is what most buyers actually want.
The general case is well covered; this is the awkward specific one.
Adding the boring version of submitting a sample, because the interesting version keeps getting posted and the boring one is usually right.
Check the ordinary explanations, in order, and stop when one of them accounts for what you are seeing. Most of the time the second one does.
Confirming post #95 from a second method, which matters more than confirming it from a second person.
Before the thread moves on from submitting a sample — what is the sample size behind the claim? I am not being difficult; I have seen the same figure quoted from an n of four and from an n of four hundred.
Collapsed as off-topic by two members at trust level 3 or above
Post #95 describes the usual case. This is about the unusual one.
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.
Correct me on the arithmetic if it is wrong; I would rather know.
Adding a note of thanks rather than an opinion. I did not know most of that.
Everything in post #95 holds. The case it does not cover is the one I have.
Submitting a sample 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.
The documentation on submitting a sample is better than this thread and I say that as someone who has posted in the thread.
On post #99 — agreed on the reasoning, with one qualification.
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.
That has been true for the cases I have seen and I have not seen many.
Picking up post #103: that is the part I would want checked first.
The record shows what was measured. Everything beyond that is inference and this site tries to keep the line visible.
It is the sort of thing that seems obvious in retrospect and was not at the time.
Helpful, and short, which on this subject is harder than long.
Post #103 is the version of this I will quote in future. One addition.
A record with four results over sixteen months is a thin record rather than a bad one, and the honest description says which.
The interesting part of this is the exception, and I do not understand the exception.
Collapsed as off-topic by two members at trust level 3 or above
Post #103 describes the usual case. This is about the unusual one.
Submitting a sample has a well-known answer and a correct answer, and the interesting work is establishing that they are the same. Nobody has done that here yet.
Post #108 put the caveat in the right place and I want to underline it.
Repeat determination on the same product line months apart is the measurement that speaks to consistency, and consistency is what most buyers actually want.
That holds under the stated conditions and I have stated them.
The arithmetic on submitting a sample is the easy part and it is where the errors are, which is an uncomfortable combination. Show your working and someone will catch it.
Where I would push back on the submitting a sample consensus is the confidence, not the direction. The direction looks right. The confidence is borrowed.
Small methodological point on submitting a sample: repeating a measurement is cheap and resolves most of what is being argued about here at no cost to anyone.
Everything in post #112 holds. The case it does not cover is the one I have.
An honest declaration on submitting a sample: I have a prior here and it is strong enough that you should weight what I say downward. Stating it rather than hiding it.
Reading rather than contributing, but this is the most useful thread I have found on it.
This topic was referenced in
- What a documentation review can and cannot tell youSourcing › Independent verification · 83 replies
- Choosing which test to pay for, given a fixed budget — does this still hold?Sourcing › Independent verification · 39 replies
- Revisiting: Aggregate verification data across the directory, with caveatsSourcing › Independent verification · 26 replies
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