Re: SPSS Syntax MIXED Model

Posted by Ryan on
URL: http://spssx-discussion.165.s1.nabble.com/SPSS-Syntax-MIXED-Model-tp5713934p5714056.html

Zalihe,

 

A few very brief comments:

 

(1) The REPEATED statement [as currently written] in the 3rd model is likely overkill AND inappropriate since the levels of "observation_point" do not mean the same thing for each subject. The RANDOM statement is accounting for differences between subjects with respect to intercepts at t=0 and linear trajectories (aka slopes). Let me be more direct...Within subject correlation due to repeated measures (multiple observations per subject) is being accounted for by the RANDOM statement.

 

(2) I cannot pinpoint from over here why model 2 cannot be handled by the MIXED procedure in SPSS on your machine. If you have access to SAS, then you might consider the HPMIXED procedure. The HPMIXED procedure is a fairly recent procedure in SAS which is designed to handle complex models and large datasets. OTOH, the fixed effects component of your second model does seem to be getting quite large. You might need to remind yourself about what the primary research question is and whether you really need all of those fixed effects in order to answer it. Don't lose the forest for the trees.

 

(3) The default estimation method is REML. Why do you keep changing it to ML? Is it to conduct likelihood ratio tests to compare nested models? If not, you might consider going back to the default estimation method; it is generally the preferred choice.

 

Ryan

On Fri, Jul 6, 2012 at 10:24 AM, Zalihe <[hidden email]> wrote:

Dear Ryan,

I am so sorry but i have realized that i have copied you the wrong syntaxes
in the previous e-mail.

The first code i have mentioned which have worked is;

MIXED eGFR_Value BY Gender Ethnicity WITH Age Time

  /CRITERIA = CIN(95) MXITER(150) MXSTEP(5) SCORING(1)
  SINGULAR(0.000000000001) HCONVERGE(0, ABSOLUTE) LCONVERGE(0, ABSOLUTE)
  PCONVERGE(0.000001, ABSOLUTE)
  /FIXED = Gender Ethnicity Age Time Gender*Time Ethnicity*Time Age*Time |
SSTYPE(3)
  /METHOD = ML
  /PRINT = G R SOLUTION TESTCOV
  /RANDOM = INTERCEPT Time | SUBJECT(ID) COVTYPE(UN).

The second code which i have tried and couldn't be able to make it working
is;

MIXED eGFR_Value  BY Gender Ethnicity Hypertension_diagnosis

Diabetes_Diagnosis IHD_Diagnosis Anaemia_Diagnosis Obesity_Diagnosis WITH
Age Time

  /CRITERIA = CIN(95) MXITER(150) MXSTEP(5) SCORING(1)
  SINGULAR(0.000000000001) HCONVERGE(0, ABSOLUTE) LCONVERGE(0, ABSOLUTE)
  PCONVERGE(0.000001, ABSOLUTE)
  /FIXED = Gender Ethnicity Age Hypertension_diagnosis Diabetes_Diagnosis

IHD_Diagnosis Anaemia_Diagnosis Obesity_Diagnosis Gender*Time Ethnicity*Time
Hypertension_diagnosis*Time Diabetes_Diagnosis*Time IHD_Diagnosis*Time
Anaemia_Diagnosis*Time Obesity_Diagnosis*Time Age*Time | SSTYPE(3)

  /METHOD = ML
  /PRINT = G R SOLUTION TESTCOV
  /RANDOM = INTERCEPT Time| SUBJECT(ID) COVTYPE(UN).

The third code which is agaion gave me the same error is;

MIXED eGFR_Value  BY Gender Ethnicity Hypertension_diagnosis
Diabetes_Diagnosis IHD_Diagnosis Anaemia_Diagnosis Obesity_Diagnosis

Observation_point
WITH Age Time

  /CRITERIA = CIN(95) MXITER(150) MXSTEP(5) SCORING(1)
  SINGULAR(0.000000000001) HCONVERGE(0, ABSOLUTE) LCONVERGE(0, ABSOLUTE)
  PCONVERGE(0.000001, ABSOLUTE)
  /FIXED = Gender Ethnicity Age Hypertension_diagnosis Diabetes_Diagnosis

IHD_Diagnosis Anaemia_Diagnosis Obesity_Diagnosis Gender*Time Ethnicity*Time
Hypertension_diagnosis*Time Diabetes_Diagnosis*Time IHD_Diagnosis*Time
Anaemia_Diagnosis*Time Obesity_Diagnosis*Time Age*Time | SSTYPE(3)

  /METHOD = ML
  /PRINT = G R SOLUTION TESTCOV

  /RANDOM = INTERCEPT Time| SUBJECT(ID) COVTYPE(UN)
  /REPEATED = Observation_point  | SUBJECT(ID) COVTYPE(UN) .

If you can comment on my problem when you have time, i will be pleased.
Thank you so much and so sorry again for confusion.

Kind Regards,

Zalihe.

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