Bioequivalence and Bioavailability Forum • QCs vs. calibrators

QCs vs. calibrators [Bioanalytics]

posted by Helmut – Vienna, Austria, 2010-01-19 22:49 (6006 d 15:42 ago) – Posting: # 4622
Views: 9,551

Dear Ohlbe!

❝ ❝ Of course the value has to be reported and included in the calculation of acc./prec.

❝

❝ Then we agree: you're not excluding it...

❝

❝ Of course I agree that you can have up to 1/3 of your QCs failing.

OK.

❝ But that's not what I call exclusion. The failing results are there, and should be reported and included in the calculations, whether considered statistically to be outliers or not.

Again, an outlier test with n=2–3 is futile. IMHO such a test shouldn’t be used in any case. To be honest I don’t know of any analyst even trying one. Well, and results should be reported. But: In this post you wrote:

❝ You may exclude a standard sample, but I can't see how you could exclude a QC, unless you have an excellent and documented analytical reason to do it.

❝ […] Your QC result is an experimental result […]

Again, what’s your rationale of “excluding a standard sample” – calibrators and QCs are prepared in exactly the same way? Both are spiked samples of known concentrations. If you ask for an “excellent and documented analytical reason” to exclude a QC, why do you not require the same for standards? Or do you? To paraphrase your statement: Your calibrator is an experimental result […]

—
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Helmut Schütz

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Complete thread:

outliers test for QC sample mathews 2007-10-11 07:58
- outliers test - but not for QCs! Helmut 2007-10-11 15:31
  - Outlier test - but not for QC's yuvrajkatkar 2010-01-19 08:49
    - Outlier test - but not for QC's H_Rotter 2010-01-19 12:55
    - Outlier tests: forget it! Helmut 2010-01-19 17:36
      - Outlier tests: forget it! Ohlbe 2010-01-19 19:00
        
        Outlier tests: forget it! Helmut 2010-01-19 19:16
        
        Outlier tests: forget it! Ohlbe 2010-01-19 21:00
        
        QCs vs. calibratorsHelmut 2010-01-19 21:49
        
        QCs vs. calibrators Ohlbe 2010-01-20 19:01
        
        QCs vs. calibrators Helmut 2010-01-20 19:26
        
        QCs vs. calibrators Ohlbe 2010-01-20 19:52
        
        Two thirds of QCs H_Rotter 2010-01-20 16:21
        
        Two thirds of QCs Ohlbe 2010-01-20 18:49
        
        Outlier tests: forget it!....what if.... moblak 2010-01-25 10:04
        
        Outlier tests: forget it!....what if.... Ohlbe 2010-01-25 23:19