The arithmetic in post #3 is right; the assumption feeding it is the part to check.
My position on inter-laboratory comparison is current rather than settled. I have revised it once already and I expect to again, so treat it accordingly.
Narrowing post #7, because the general version has more than one answer.
I read the earlier replies on inter-laboratory comparison twice before writing this, because I had assumed the opposite and wanted to be sure I was disagreeing with what was said rather than what I expected.
Where I part company with post #14, and it is a narrow parting.
An independent laboratory's method being different from the supplier's is not a discrepancy. It becomes one only when the results differ by more than both methods' demonstrated precision.
That is the version I use. It may not be the version that is correct.
Post #19 and I disagree about the size of the effect, not about the direction.
A stability-indicating method is one demonstrated to resolve the analyte from its degradation products, usually through forced degradation. Calling a method stability-indicating without that work is a claim rather than a property.
Read the full topic (29 posts)
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About the Method validation category
Specificity, linearity, precision, accuracy, robustness, system suitability, and why two labs disagree. This post is a community wiki: any member at trust level 3 or above can edit it, and every edit is…
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+1 | 5 | 468 | 5mo |
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Sample handling between despatch and injection
Sample handling between despatch and injection Writing it up because I had to work it out twice and would rather nobody else did. Trying to work out what would count as evidence on sample handling between…
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+63 | 68 | 2.4k | 3mo |
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LOD and LOQ: definitions people get wrong
LOD and LOQ: definitions people get wrong — setting out what I have, and where I think it stops being reliable. What changes if the standard account of LOD and LOQ is wrong? I ask because I have been treating…
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2 | 43k | 8mo | |
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Revisiting: Sample handling between despatch and injection
Posting this under the heading it deserves: Revisiting: Sample handling between despatch and injection Everything below is what sits behind that. Reading back through what has been written here about Sample…
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+5 | 9 | 1.1k | 6mo |
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Validating a method you did not develop
On the subject in the title: Validating a method you did not develop Working notes rather than a conclusion. What changes if the standard account of validating a method is wrong? I ask because I have been…
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+10 | 14 | 15k | 3mo |
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Validating a method you did not develop
On the subject in the title: Validating a method you did not develop Working notes rather than a conclusion. What changes if the standard account of validating a method is wrong? I ask because I have been…
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+10 | 14 | 15k | 3mo |
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Shoulders, tangent skims, and defensible integration — the long version
Shoulders, tangent skims, and defensible integration — the long version Writing it up because I had to work it out twice and would rather nobody else did. Setting out an integration problem with the actual…
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+16 | 20 | 27k | 3mo |
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What consumer-accessible tests can and cannot determine — a second dataset
What consumer-accessible tests can and cannot determine — a second dataset I have a specific reason for asking rather than idle curiosity, and the context is below. Posting a small dataset on…
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+117 | 131 | 45k | 10h |
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Relative retention time as a better inter-laboratory comparator
On the subject in the title: Relative retention time as a better inter-laboratory comparator Working notes rather than a conclusion. What changes if the standard account of relative retention time is wrong? I…
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+7 | 11 | 28k | 14mo |
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Coming back to: Where the integrator drew the baseline, and how much it moved the number
On the subject in the title: Where the integrator drew the baseline, and how much it moved the number Working notes rather than a conclusion. Posting the method first, because I know what the first three…
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+20 | 24 | 2.7k | 10mo |