RE: [NMusers] Sensitive analysis

2012-02-19 Thread Standing Joseph (GREAT ORMOND STREET HOSPITAL FOR CHILDREN NHS TRUST)
Norman, Have a look at log-likelihood profiling in PsN. LLP documentation is on the PsN website - I don't think it quite does what you want (it will look for parameter values that give significant OFV changes rather than changing parameters by certain proportions). Best wishes, Joe Joseph F St

[NMusers] UK Academic Post - expressions of interest closing date 31st January

2012-01-23 Thread Standing Joseph (GREAT ORMOND STREET HOSPITAL FOR CHILDREN NHS TRUST)
Dear NMUsers, University of London School of Pharmacy recently merged with University College London. Expressions of interest are being sought for senior (Reader/Professor) researchers to apply for new posts that are being created. I am posting this on NMUsers in the hope that someone current

[NMusers] RE: Bootstrap in combination with PRIOR?

2011-12-22 Thread Standing Joseph (GREAT ORMOND STREET HOSPITAL FOR CHILDREN NHS TRUST)
Jacob, I am guilty of having performed such a bootstrap (but didn't do any of the testing you describe). Anyway, here's an opinion: By using prior in nonmem you are trying to get an approximation of what the pooled data fit would be and get an OFV that is theoretically the same as if you did

RE: [NMusers] Parent and metabolite model-residual error model and L2

2011-09-02 Thread Standing Joseph (GREAT ORMOND STREET HOSPITAL FOR CHILDREN NHS TRUST)
I have a follow on question - has anyone used L2 with the M3 method for BLQ handling? Here is my $ERROR code which works fine when I ignore L2: $ERROR IPRED = 0 LOQ=LLOQ IF(ANALY.EQ.1) IPRED=A(3)/VD IF(ANALY.EQ.2) IPRED=A(4)/VDM IF(ANALY.EQ.1) SIG=THETA(9)*IPRED IF(ANALY.EQ.2) SIG=THETA(10)*

RE: [NMusers] PK and PD variability

2011-03-11 Thread Standing Joseph (GREAT ORMOND STREET HOSPITAL FOR CHILDREN NHS TRUST)
Dear Andreas, When you say you add IIV on dose, I'm not sure exactly what you mean but suggest you need to take a 2 step approach. In order to replicate variability in dose, you will need to simulate doses with variability, and then in a second step use these simulated doses to estimate the Em

RE: [NMusers] [Fwd: occasions during pregnancy]

2011-03-02 Thread Standing Joseph (GREAT ORMOND STREET HOSPITAL FOR CHILDREN NHS TRUST)
Hi Paul, As I understand it, you don't have data from all trimesters in all subjects (and anyhow categorising your data like this may not be helpful), so I don't think it is appropriate to constrain occasions to correspond to trimesters. I would include an OCC column which increases for every

RE: [NMusers] Growth Curve Modelling

2011-02-17 Thread Standing Joseph (GREAT ORMOND STREET HOSPITAL FOR CHILDREN NHS TRUST)
Nyashadzaishe, UK and I believe WHO growth charts are derived using LMS method which you can do in R - look for papers by TJ Cole. I also suspect you might get a response from a certain NHG Holford telling you to look at his NONMEM method: Paediatr Anaesth. 2011 Mar;21(3):309-15 - I have only s

[NMusers] RE: Rounding errors with TRANSIT model

2010-08-11 Thread Standing Joseph (Great Ormond Street Hospital For Children NHS Trust)
Ann I think your model is starting to be over-parameterised: 4 compartments plus lag plus transit (have you plotted the individual alag estimates as they have fairly big omegas?) I think if you cannot describe the data well with a 4 comp linear model, and are seeing differences in PK with diffe

RE: [NMusers] nm7 IMP method question

2010-05-13 Thread Standing Joseph (Great Ormond Street Hospital For Children NHS Trust)
Desr Ethan, It is my understanding that you should do an IMP step with EONLY=1 in order to get an OFV to be used for hypothesis testing after a SAEM step, as the SAEM OFV cannot be used for likelihood ratio tests. I think your problem is that the first IMP step has converged (you asked for CTY