Mixed Effects Model for log CD4

AIDS Clinical Trial Group (ACTG) 193A Study

 

The Mixed Procedure

 

Model Information

Data Set

WORK.CD4

Dependent Variable

logcd4

Covariance Structure

Unstructured

Subject Effect

id

Estimation Method

REML

Residual Variance Method

Profile

Fixed Effects SE Method

Model-Based

Degrees of Freedom Method

Containment

 

Class Level Information

Class

Levels

Values

id

1309

not printed

 

Dimensions

Covariance Parameters

7

Columns in X

5

Columns in Z Per Subject

3

Subjects

1309

Max Obs Per Subject

9

Observations Used

5036

Observations Not Used

0

Total Observations

5036

 

Iteration History

Iteration

Evaluations

-2 Res Log Like

Criterion

0

1

14981.51659156

 

1

3

11935.53693907

0.00040624

2

1

11934.96765938

0.00000185

3

1

11934.96517062

0.00000000

 

Convergence criteria met.

 

Estimated G Matrix

Row

Effect

id

Col1

Col2

Col3

1

Intercept

1

0.5857

0.007254

-0.01235

2

week

1

0.007254

0.000923

-0.00092

3

week_16

1

-0.01235

-0.00092

0.001240

 

Estimated G Correlation Matrix

Row

Effect

id

Col1

Col2

Col3

1

Intercept

1

1.0000

0.3120

-0.4581

2

week

1

0.3120

1.0000

-0.8584

3

week_16

1

-0.4581

-0.8584

1.0000

 

Covariance Parameter Estimates

Cov Parm

Subject

Estimate

Standard Error

Z Value

Pr Z

UN(1,1)

id

0.5857

0.03475

16.85

<.0001

UN(2,1)

id

0.007254

0.001805

4.02

<.0001

UN(2,2)

id

0.000923

0.000160

5.76

<.0001

UN(3,1)

id

-0.01235

0.002730

-4.52

<.0001

UN(3,2)

id

-0.00092

0.000236

-3.90

<.0001

UN(3,3)

id

0.001240

0.000395

3.14

0.0008

Residual

 

0.3062

0.01007

30.39

<.0001

 

Fit Statistics

-2 Res Log Likelihood

11935.0

AIC (smaller is better)

11949.0

AICC (smaller is better)

11949.0

BIC (smaller is better)

11985.2

 

 

Solution for Fixed Effects

Effect

Estimate

Standard Error

DF

t Value

Pr > |t|

Intercept

2.9415

0.02562

1308

114.81

<.0001

week

-0.00734

0.001987

1185

-3.70

0.0002

week_16

-0.01204

0.003174

1004

-3.79

0.0002

week*trt

0.02685

0.003847

1534

6.98

<.0001

week_16*trt

-0.02774

0.006198

1534

-4.47

<.0001