Mixed Effects Model for Percent Body Fat with Random Intercept and Slopes before and after Menarche

MIT Growth and Development Study

 

The Mixed Procedure

 

Model Information

Data Set

WORK.FAT

Dependent Variable

pbf

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

162

not printed

 

Dimensions

Covariance Parameters

7

Columns in X

3

Columns in Z Per Subject

3

Subjects

162

Max Obs Per Subject

10

Observations Used

1049

Observations Not Used

0

Total Observations

1049

 

Iteration History

Iteration

Evaluations

-2 Res Log Like

Criterion

0

1

7073.41750695

 

1

2

6063.49976979

0.00045902

2

1

6062.44105637

0.00001857

3

1

6062.40145176

0.00000004

4

1

6062.40136458

0.00000000

 

Convergence criteria met.

 

Estimated G Matrix

Row

Effect

id

Col1

Col2

Col3

1

Intercept

1

45.9413

2.5263

-6.1096

2

time

1

2.5263

1.6311

-1.7505

3

time_0

1

-6.1096

-1.7505

2.7497

 

Estimated G Correlation Matrix

Row

Effect

id

Col1

Col2

Col3

1

Intercept

1

1.0000

0.2918

-0.5436

2

time

1

0.2918

1.0000

-0.8266

3

time_0

1

-0.5436

-0.8266

1.0000

 

Covariance Parameter Estimates

Cov Parm

Subject

Estimate

Standard Error

Z Value

Pr Z

UN(1,1)

id

45.9413

5.7393

8.00

<.0001

UN(2,1)

id

2.5263

1.2185

2.07

0.0382

UN(2,2)

id

1.6311

0.4331

3.77

<.0001

UN(3,1)

id

-6.1096

1.8730

-3.26

0.0011

UN(3,2)

id

-1.7505

0.5980

-2.93

0.0034

UN(3,3)

id

2.7497

0.9635

2.85

0.0022

Residual

 

9.4732

0.5443

17.40

<.0001

 

Fit Statistics

-2 Res Log Likelihood

6062.4

AIC (smaller is better)

6076.4

AICC (smaller is better)

6076.5

BIC (smaller is better)

6098.0

 

 

Solution for Fixed Effects

Effect

Estimate

Standard Error

DF

t Value

Pr > |t|

Intercept

21.3614

0.5646

161

37.84

<.0001

time

0.4171

0.1572

161

2.65

0.0087

time_0

2.0471

0.2280

159

8.98

<.0001

 

Type 3 Tests of Fixed Effects

Effect

Num DF

Den DF

Chi-Square

F Value

Pr > ChiSq

Pr > F

time

1

161

7.04

7.04

0.0080

0.0087

time_0

1

159

80.64

80.64

<.0001

<.0001