The opening post put the caveat in the right place and I want to underline it.
Agreed on repeatability versus intermediate precision, 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.
Worth separating two things that post #11 runs together.
On repeatability versus intermediate precision, the part that usually goes wrong is that the question is asked as though it has one answer. It has a range, and the width of the range is the interesting bit.
If you can post the two or three numbers you are working from, several people here will check the arithmetic rather than argue about the conclusion.
An observation about repeatability versus intermediate precision that I cannot explain and am posting anyway, on the principle that unexplained observations are more useful public than private.
On post #46 — agreed on the reasoning, with one qualification.
Distinguishing three things in the repeatability versus intermediate precision discussion that keep getting used interchangeably: the observation, the proposed mechanism, and the recommendation that gets attached to both.
My position on repeatability versus intermediate precision is current rather than settled. I have revised it once already and I expect to again, so treat it accordingly.
What would change my mind on repeatability versus intermediate precision is a second dataset collected by someone with no stake in the first. Until then I hold it loosely and I would rather say so than pretend to more.
Precision and repeatability: within-run and between-run variability of the method. Acceptance criterion is typically a relative standard deviation of ≤2% for area measurements.
I would put a moderate confidence on that and no more.
Post #133 put the caveat in the right place and I want to underline it.
Where a pharmacopoeial monograph exists, a method that follows it inherits a great deal of assurance. Almost nothing discussed here has one.
Read the full topic (135 posts)
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About the Method validation category
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+1 | 5 | 468 | 5mo |
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When to suspect the method rather than the sample
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+109 | 115 | 63k | 15mo |
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Second pass at: Robustness: the parameters worth deliberately varying
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Revisiting: Spike-and-recover accuracy for a peptide assay
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2 | 6.8k | 21h | |
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What a stability-indicating method is and how you demonstrate one
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Repeatability versus intermediate precision — what changed since
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Coming back to: Where the integrator drew the baseline, and how much it moved the number
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Why quantitation is the hard part, not detection
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+11 | 15 | 27k | 12mo |
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Relative retention time as a better inter-laboratory comparator — does this still hold?
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+11 | 15 | 21k | 21mo |
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Coming back to: What consumer-accessible tests can and cannot determine
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+4 | 8 | 25k | 22mo |