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Re: a question about the mixture distribution

From: wu kehua <zckehua>
Date: Tue, 13 Oct 2009 11:58:01 -0500

Hi Matt,

Thank you very much for your kindly reply. It is very helpful.

I still have another question about this issue. I have tried the first
option. I applied three subgroups on ALPH and two subgroups on BASE. I think
there should be six subgroups in total, right? But in the resulting data,
there are just five subgroups. The code follows,

$PRED

    CALLFL =1
   EST = MIXEST
  IF (MIXNUM.EQ.3) THEN
  ALPH = (THETA(3))
  END IF
  IF (MIXNUM.EQ.2) THEN
  ALPH = (THETA(2))
  END IF
  IF (MIXNUM.EQ.1) THEN
  ALPH = (THETA(1))
  ENDIF


  IF (MIXNUM.EQ.4) THEN
  BASE=THETA(4)
ELSE
 BASE=THETA(5)
END IF



$MIX

    P(1) = THETA(6)
   P(2)=THETA(7)
    P(3) = 1-THETA(7)-THETA(6)
    P(4)=THETA(8)
    P(5)=1-THETA(8)
    NSPOP = 5

Sorry to bother you and thank you very much. I will try that one mentioned
in your mail and let you know the results.
I appreciate your helps.

Best regards,

Kehua

2009/10/13 Fidler,Matt,FORT WORTH,R&D <Matt.Fidler

> Kehua,
>
> Option 1 is definitely better. This states that there is a possibility
> that a population falls into ALPH1 or ALPH2. Within that same population
> there are two populations for BASE.
>
> The other option states that each person in the has distinct parameters
> that four populations fall into: ALPH - Pop1, ALPH - Pop 2, Base -Pop 1, or
> Base -Pop2. Therefore, if you selected ALPH - pop1, you wouldn't have the
> parameter base. (You require this by having P1 - P4 to add up to be one -
> the total probability).
>
> A third option you may consider is if you have reason to believe that the
> populations that have ALPH1 and Base1 are the same:
>
> $PRED
> IF (MIXNUM.EQ.2) THEN
> ALPH =THETA(1)
> ELSE
> ALPH = THETA(2)
> ENDIF
>
> IF (MIXNUM.EQ.2) THEN
> BASE=THETA(3)
> ELSE
> BASE=THETA(4)
> END IF
>
> $MIX
>
> P(1) = THETA(5)
> P(2) = 1-THETA(5)
> NSPOP = 2
>
> I haven't run anything like Option 1, and am unsure if NONMEM supports two
> separate populations for ALPH and BASE. Has anyone tried this?
>
> Matt.
>
>
> ------------------------------
> *From:* owner-nmusers
> *On Behalf Of *wu kehua
> *Sent:* Tuesday, October 13, 2009 10:58 AM
> *To:* nmusers
> *Subject:* [NMusers] a question about the mixture distribution
>
> Hi,
>
> I am a new NONMEM user. I have a question about mixture distribution.
>
> I have two parameters. How to apply mixture distribution on the both
> parameters? I should use the first one or the second one?
>
> *First,*
> $PRED
> IF (MIXNUM.EQ.2) THEN
> ALPH =THETA(1)
> END IF
> IF (MIXNUM.EQ.1) THEN
> ALPH = THETA(2)
> ENDIF
>
> IF (MIXNUM.EQ.3) THEN
> BASE=THETA(3)
> ELSE
> BASE=THETA(4)
> END IF
>
> $MIX
>
> P(1) = THETA(5)
> P(2) = 1-THETA(5)
> P(3)=THETA(6)
> P(4)=1-THETA6)
> NSPOP = 4
>
>
> *Second,*
>
> IF (MIXNUM.EQ.1) THEN
> ALPH =THETA(1)
> BASE=THETA(3)
> END IF
> IF (MIXNUM.EQ.2) THEN
> ALPH = THETA(1)
> BASE=THETA(4)
> ENDIF
> IF (MIXNUM.EQ.3) THEN
> ALPH = THETA(2)
> BASE=THETA(3)
> ELSE
> ALPH = THETA(2)
> BASE=THETA(4)
> END IF
>
> $MIX
>
> P(1) = THETA(5)
> P(2) = THETA(6)
> P(3)=THETA(7)
> P(4)=1-THETA(5)-THETA(6)-THETA(7)
> NSPOP = 4
>
> Thank you very much!
>
> Best regards,
>
> Kehua
>
>
>
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Received on Tue Oct 13 2009 - 12:58:01 EDT

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