Local maximum of LogL
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Local maximum of LogL

Dear Hermann,

If you are actually using a GLMM, then I can believe the numbers
because the LogL value printed is not really what is being minimised.
i.e. it only holds the 'Conditional Normal' part of the model.

If you are fitting a Normal model, then there must be something
going wrong but you have not given enough information for me to detect it.

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Date: Wed, 19 Jul 2000 15:04:47 -0400
From: "C. Balde" <cbalden@entelchile.net>
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To: asreml <asreml@chiswick.anprod.csiro.au>
Subject: Local maximum of LogL
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Dear Arthur, Dear All,

When fitting a univariate model I get the following problem: The LogL
function converge at a maximum value. Sometimes  the value decreases in
every iteration and sometimes it first increases and then decreases, but
the final value is not the maximum. Changing the initial values or using
!GU option makes the LogL to increase in every itration, but the final
value is the same as in prior run.

So I think ASREML has found a local maximum, but not the global maximum.
Is this right ? Any sugestion on how to solve this problem ?


PS: Following are the LogL values so you can understan my questions.

LogL=-1177.45     S2=  5.1233        802 df   0.1000     0.1000

 LogL=-1177.60     S2=  4.9262        802 df   0.1277     0.1299

 LogL=-1178.34     S2=  4.6714        802 df   0.1730     0.1699

 LogL=-1179.18     S2=  4.4919        802 df   0.2145     0.1949

 LogL=-1179.47     S2=  4.4425        802 df   0.2288     0.1993

 LogL=-1179.50     S2=  4.4371        802 df   0.2305     0.1996

 LogL=-1179.50     S2=  4.4366        802 df   0.2306     0.1996


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Arthur Gilmour PhD                  mailto:Arthur.Gilmour@agric.nsw.gov.au
Principal Research Scientist (Biometrics)            fax: <61> 2 6391 3899
NSW Agriculture                                           <61> 2 6391 3922
Orange Agricultural Institute             telephone work: <61> 2 6391 3815
Forest Rd, ORANGE, 2800, AUSTRALIA                  home: <61> 2 6362 0046

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