RE: OFV or Diagnostic Plot ?? Which one rules...
Hi Sumeet,
The OFV is often king. But what does the VPC look like? That is the gold
standard. Diagnostic plots are equivalent to Rorschach blots.
If you find a way to let us see the VPCs then we can all enjoy the view.
Best wishes,
Nick
Holford NHG. The visual predictive check - superiority to standard diagnostic
(Rorschach) plots www.page-meeting.org/?abstract=738. Last accessed 13 Feb
2019. PAGE. 2005;14.
Nguyen TH, Mouksassi MS, Holford N, Al-Huniti N, Freedman I, Hooker AC, et al.
Model Evaluation of Continuous Data Pharmacometric Models: Metrics and
Graphics. CPT: pharmacometrics & systems pharmacology. 2017;6(2):87-109.
Quoted reply history
From: [email protected] <[email protected]> On Behalf Of
Singla, Sumeet K
Sent: Wednesday, 13 February 2019 7:28 PM
To: [email protected]
Subject: [FORGED] [NMusers] OFV or Diagnostic Plot ?? Which one rules...
Hi Everyone,
I am fitting two compartment PK model to Marijuana (THC) concentrations. When I
apply proportional error (or proportional plus additive) residual model, I get
pretty good fits (except 15% of subjects) at all time points.
However, when I apply only additive error residual model, I get perfect fits in
all subjects but objective functional value is increased by about 20 units. DV
vs IPRED reveal all concentrations on line of unity.
My question is: should I go with additive error model which gives me perfect
fit but higher OFV or should I go with proportional error model which gives me
lower OFV but not so good fit in couple of subjects?
Regards,
Sumeet Singla
Graduate Student
Dpt. of Pharmaceutics & Translational Therapeutics
College of Pharmacy- University of Iowa