RE: [NMusers] Hessian of posterior density is non positive definite during search

Hello Everyone Huge thanks to Peter, Jeroen, Leonid, Jonathan, Nick, Matt, Marc, Andreas, Kyun-Seop, Shelley and all, for taking the time to look at my problem and for offering me such detailed and helpful advice, much appreciated. Apologies for the delay in replying, teaching duties have kep

RE: [NMusers] Hessian of posterior density is non positive definite during search

Hessian of posterior density is non positive definite during search Dear Matt & All I?m still battling I?m afraid? Can?t seem to get past the SUM OF "SQUARED" WEIGHTED INDIVIDUAL RESIDUALS IS INFINITE problem. I?ve now log-transformed my data, and deleted all but the firs

Re: [NMusers] Hessian of posterior density is non positive definite during search

Ann, Several ideas: 1. Fix ALAGs to zero, will it help? 2. Try to shield IPRED from being zero IPRED=LOG(0.0001) IF(F.GT.0.0001) IPRED=LOG(F) Y=IPRED + SIG1*ERR(1) (this could be a bad style, but will allow you to test the code) 3. Try ADVAN6, 8, 13 4. Remove BQL part, fit it as a 3-comp linea

RE: [NMusers] Hessian of posterior density is non positive definite during search

Dear Matt & All I'm still battling I'm afraid... Can't seem to get past the SUM OF "SQUARED" WEIGHTED INDIVIDUAL RESIDUALS IS INFINITE problem. I've now log-transformed my data, and deleted all but the first occurrence of a BQL data point from each individual. I'm confident that the initial e

Re: [NMusers] Hessian of posterior density is non positive definite during search

appreciated J All best wishes Ann *From:*owner-nmus...@globomaxnm.com [mailto:owner-nmus...@globomaxnm.com] *On Behalf Of *Nick Holford *Sent:* Friday, 29 October, 2010 11:50 *To:* 'nmusers@globomaxnm.com' *Subject:* Re:

RE: [NMusers] Hessian of posterior density is non positive definite during search

mbridge Center Cambridge, MA 02142 Ann Rigby-Jones Sent by: owner-nmus...@globomaxnm.com 29-Oct-2010 10:03 AM Message Size: 32.5 KB To "'nmusers@globomaxnm.com'" cc Subject RE: [NMusers] Hessian of posterior density is non positive definite during search Dear Nick

Re: [NMusers] Hessian of posterior density is non positive definite during search

ord *Sent:* Friday, 29 October, 2010 11:50 *To:* 'nmusers@globomaxnm.com' *Subject:* Re: [NMusers] Hessian of posterior density is non positive definite during search Ann, This error message usually means try NONMEM thinks your OMEGA initial estimates are weird. A leading suspect

RE: [NMusers] Hessian of posterior density is non positive definite during search

m.com' Subject: Re: [NMusers] Hessian of posterior density is non positive definite during search Ann, This error message usually means try NONMEM thinks your OMEGA initial estimates are weird. A leading suspect would be the OMEGA estimates for the two lag time parameters. Try fixing b

Re: [NMusers] Hessian of posterior density is non positive definite during search

Ann, This error message usually means try NONMEM thinks your OMEGA initial estimates are weird. A leading suspect would be the OMEGA estimates for the two lag time parameters. Try fixing both of them to zero and see if that gets your model going. If that doesn't work then you could try fixin

[NMusers] Hessian of posterior density is non positive definite during search

Hello NMUsers I am trying to reanalyse some data using the M3 method (Ahn et al, Likelihood based approaches to handling data below the quantification limit using NONMEM VI, J Pharmacokinet Pharmacodyn. 2008). I had previously used M6 and wanted to try something potentially more robust. I'm h