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RE: [NMusers] bootstrap

From: Nick Holford <n.holford_at_auckland.ac.nz>
Date: Sat, 11 May 2019 14:52:43 +0000

Hi Niurys,

I don't see any reason why the bootstrap won't work. Its only the IDs that are selected randomly so the FLAGs will work just the same as in the full data set.

Good luck,
Nick

-----Original Message-----
From: owner-nmusers_at_globomaxnm.com <owner-nmusers_at_globomaxnm.com> On Behalf Of Niurys.CS
Sent: Saturday, 11 May 2019 4:33 PM
To: Bill Denney <wdenney_at_humanpredictions.com>
Cc: nmusers <nmusers_at_globomaxnm.com>
Subject: Re: [NMusers] bootstrap

Dear Nick and Bill,

Thank you for your answers, and please apologize me for din´t give you information about my model.
 I share with you part of my code as well as some results. My model corresponds to QSS with constant Rtot approximation of TMDD The parameter estimates obtained with this model are pausible, and are similar to prevuios study (Rodriguez L et al, 2015). The GOF and VPC look good.
The FLAGS correspond to some outliers based on DV of some IDs (concentration of product). So, I don´t know if excluding these values, the boostrap will work correctly.

;----------------------------------
$DATA data_19.csv IGNORE=_at_
IGNORE=(FLAG.EQ.2) IGNORE=(FLAG.EQ.3)

;----------------------------------
$SUBROUTINE ADVAN13 TOL=9
;----------------------------------
$MODEL COMP=(CENTRAL) COMP=(PERIPH1) COMP(PERIPH2)
;----------------------------------
$PK

TVCL= THETA(1)
TVV1= THETA(2)
TVQ = THETA(3)
TVV2 = THETA (4)
TVKSS = THETA (5)
TVKINT = THETA (6)
IF(DOS.EQ.50) TVRMAX= 0.175
IF(DOS.GT.50)TVRMAX=THETA(7)

CL = TVCL;*EXP(ETA(1))
V1 = TVV1*EXP(ETA(1))
Q = TVQ*EXP(ETA(2))
V2 = TVV2*EXP(ETA(3))
KSS = TVKSS;*EXP(ETA(4))
KINT = TVKINT
RMAX = TVRMAX

K = CL/V1
K12 = Q/V1
K21 = Q/V2
S1 = V1


Thank you,

Niurys

2019-05-10 12:45 GMT-05:00, Bill Denney <wdenney_at_humanpredictions.com>:
> Hi Niurys,
>
> The simplest method to ensure a good bootstrap is often to simplify
> the data file by removing rows that should not be used for the
> modeling before running the bootstrap. Notably, if you exclude an
> entire subject either based on the ID column or another column,
> usually the boostrap will not work correctly.
>
> I believe that most if not all tools generate the bootstrap with new
> ID column values (the ID is given a new sequential value based on
> sampling order). If you exclude an entire subject based on another
> column, the you will not have the expected number of subjects in the
> analysis because all the bootstrap tools that I know of don't account
> for exclusions with making the new data file.
>
> If this doesn't help, giving more info will help. (What tool are you
> using for bootstrap? What command line are you running? Can you
> share the model and a snippet of the data?)
>
> Thanks,
>
> Bill
>
> -----Original Message-----
> From: owner-nmusers_at_globomaxnm.com <owner-nmusers_at_globomaxnm.com> On
> Behalf Of Niurys.CS
> Sent: Friday, May 10, 2019 12:17 PM
> To: nmusers <nmusers_at_globomaxnm.com>
> Subject: [NMusers] bootstrap
>
> Dear nmusers,
>
>
> I have a big doubt. When I used the bootstrap to evaluate my model, I
> had some bugs. In my code I use IGNORE statements based on FLAGS for
> some outliers. I don't know if I remove these IGNORE statements, the
> bootstrap will run well. Can you give me some suggestions???????
>
>
> Regards
>
> Niurys de Castro Suárez
>
> --
>
> MSc Niurys de Castro Suárez
> Profesor Asistente Farmacometría
> Investigador Agregado
> Departamento Farmacia
> Instituto de Farmacia y Alimentos, Universidad de La Habana Cuba "Una
> estrella brilla en la hora de nuestro encuentro"
>


--

MSc Niurys de Castro Suárez
Profesor Asistente Farmacometría
Investigador Agregado
Departamento Farmacia
Instituto de Farmacia y Alimentos, Universidad de La Habana Cuba "Una estrella brilla en la hora de nuestro encuentro"

Received on Sat May 11 2019 - 10:52:43 EDT

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