Hessian error

[SONIALU]

Hello!

I am trying to model my data with more than 300 hundred patients.
Despite the predictions are good, the Hessian error continuously appears.
I have been trying to take out the patients who suggested that they could be causing the error (one each in one run) but the Hessian error still appears.
I have also tried to increase gamma.

Any other idea?

Thank you very much
Sonia

[mneely]

A Hessian error means that the model is not serving some or all patients well, among other things. Have you identified problem patients that, when removed, allow the run to proceed?

[SONIALU]

Dear Michael,

yes. I have been trying to exclude all those patients but in the last run Pmetrics is telling me
that the patients that is causing the error in number 304 and this patient is not included in the final run.ç
So, I do not know what else can I do.

Thanks
Sonia

[mneely]

If you remove patient 304 does the run complete?

[SONIALU]

It is strange... because the patient 304 had been already excluded from the previous run.. before Pmetrics gave me this message.
Sonia

[mneely]

Pmetrics numbers the patients sequentially. You have to look at the ID numbers that correspond with the subject number. For example, subject 304 could have an ID of AX440. If you removed the 304th subject, then the subject who was previously the 305th is now the 304th.

[SONIALU]

Dear Michael,
Thanks a lot,

then... after removing some patients, the ID does not correspond with the number that Pmetrics is referring?
Sonia

I have also another questions, when Pmetrics is doing NPDE or Simulations, is it using a boostrap method with replacement?