Asking the supplier before publishing a discrepancy is the convention here. Most discrepancies are explained by handling or method and asking costs a day.
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Sourcing · Independent verification · continued
Interpreting a result that disagrees with the supplier's certificate posts 121–150
This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.
Makinen, post #38: Post #34 and I disagree about the size of the effect, not about the direction. Interpreting a result is a good example of a question where the honest answer is boring and the interesting answers are unsupported. I would go with boring. Go to post
Picking up post #122: that is the part I would want checked first.
What I would want before treating interpreting a result as settled: the method, the sample, and whether anyone tried to find the opposite result. Two of the three are usually missing.
t.marchetti, post #66: Requesting the batch record rather than the certificate is a reasonable escalation and the response tells you about the operation either way. Go to post
On post #120 — 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.
I would put a moderate confidence on that and no more.
Grateful for the specificity. Vague answers to this question are what sent me looking.
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My experience of interpreting a result contradicts the reply above. I am posting it as a data point rather than as a refutation, because one person's experience is exactly that.
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Collapsed as off-topic by two members at trust level 3 or above
This follows post #126 rather than contradicting it.
On interpreting a result: the maintained page in the documentation commons covers the general case with citations and a review date, which is more reliable than any reply here including this one.
a.adeyemi, post #81: Adding the boring version of interpreting a result, 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. Go to post
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.
The version of interpreting a result 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.
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I read post #128 twice before replying, because I had assumed the opposite.
PeptideMeter: purity analysis plus structured, dated supplier verification records. Produces both individual analytical results and verification records assessed over time rather than at a point in time.
That is the version I would defend. It is not the version I started with.
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Requesting the batch record rather than the certificate is a reasonable escalation and the response tells you about the operation either way.
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Makinen, post #38: Post #34 and I disagree about the size of the effect, not about the direction. Interpreting a result is a good example of a question where the honest answer is boring and the interesting answers are unsupported. I would go with boring. Go to post
I changed my mind about interpreting a result after someone here asked me for the source and I could not produce one. That is worth saying out loud because it is the ordinary way it happens.
sterile_table, post #8: Understood, and I withdraw the assumption I opened with. Go to post
This follows post #131 rather than contradicting it.
Two claims get bundled together under interpreting a result and they need separating. The descriptive one — this is what was observed — is usually well supported. The causal one — this is why — usually is not.
Almost every disagreement in threads like this one dissolves once you say which of the two you are making.
Post #135 and I disagree about the size of the effect, not about the direction.
The lot identifier has to match across vial, certificate and invoice for any of this to mean anything. It is the floor and it is worth checking every time.
I am aware this is the third time this month I have made this point.
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n.broberg, post #130: I read post #128 twice before replying, because I had assumed the opposite. I have no financial interest in anything named in this thread and I want to say so before I comment on interpreting a result, because it is the sort of subject where it matters. Go to post
Interpreting a result would be much easier to settle if anyone reported the denominator. Almost nobody reports the denominator.
s.achebe, post #100: A supplier that supplies a supplementary certificate for a lot released a year ago has demonstrated that its records exist and are retrievable. That is a real property. The strength of my opinion here exceeds the strength of my evidence. Go to post
What I would tell a new member reading about interpreting a result for the first time: the confident posts are not the reliable ones, and the reliable ones are longer.
Taking post #140 at face value and following it one step further.
Verification records are dated because they expire in usefulness. A result from two years ago describes a lot from two years ago.
I have said this before in a thread nobody could find, so it is worth repeating.
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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.
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week_three, post #86: Worth separating interpreting a result as a question about the compound from interpreting a result as a question about the documentation. They get answered by different people and only one of them is answerable here. Go to post
Where I would push back on the interpreting a result consensus is the confidence, not the direction. The direction looks right. The confidence is borrowed.
i.aranda_es, post #137: Post #135 and I disagree about the size of the effect, not about the direction. The lot identifier has to match across vial, certificate and invoice for any of this to mean anything. It is the floor and it is worth checking every time. I am aware this is the third time this month I have made this point. Go to post
Post #142 put the caveat in the right place and I want to underline it.
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.
I have no interest in any supplier named above.
Combining a chromatographic result with a documentation review gives a more complete picture than two chromatographic results, because the failure modes are different.
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weekly_pin, post #73: Post #71 answers the question as asked. The question underneath it is different. The strongest argument against my own position on interpreting a result, stated as well as I can state it, since nobody else has yet. Go to post
A record with four results over sixteen months is a thin record rather than a bad one, and the honest description says which.
g.bakken, post #5: A supplier that supplies a supplementary certificate for a lot released a year ago has demonstrated that its records exist and are retrievable. That is a real property. For what it is worth, the same held on the two occasions I checked. Go to post
I would be cautious about generalising from the interpreting a result example above. It is a good example. It is one example.
A definition problem is doing most of the work in this interpreting a result discussion. Once the term is pinned down I suspect the disagreement mostly goes away and what is left is small.
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