NONMEM Users Network Archive

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RE: Honest measurements

From: Stephen Duffull <stephen.duffull>
Date: Mon, 24 Aug 2009 20:18:23 +1200

Mats

I agree with Nick. Negative "observed" concns do occur for assays, even in=
 my limited time working with HPLC I have seen them, however due to LOD/LOQ=
 they are never really looked for and certainly never reported...

Steve

> -----Original Message-----
> From: owner-nmusers
> nmusers
> Sent: Monday, 24 August 2009 6:25 p.m.
> To: nmusers
> Subject: [NMusers] Honest measurements
>
>
>
> Mats Karlsson wrote:
>
> << Chemists, however pushed, would never report negative
> concentrations, not
> for past studies, not for future studies. The methods they use don't
> even
> report them.>>
>
> I am working with a chemist using LC/MS who has been persuaded to look
> honestly at his data without preconceived ideas of limits of
> quantitation and detection. Indeed when he opened his eyes he found
> that his system was indeed giving negative concentration measurements
> (at times when concentrations were expected to be very low).
>
> Of course we must do other things when the data is censored by bad
> scientific practice in the chemist's lab but with honest measurments an
> additive residual error model is required.
>
> Nick
>
>
> --
> Nick Holford, Professor Clinical Pharmacology
> Dept Pharmacology & Clinical Pharmacology
> University of Auckland, 85 Park Rd, Private Bag 92019, Auckland, New
> Zealand
> n.holford
> mobile: +64 21 46 23 53
> http://www.fmhs.auckland.ac.nz/sms/pharmacology/holford
Received on Mon Aug 24 2009 - 04:18:23 EDT

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