! F1. Sibling Interaction Model
! Maternal Ratings of Children's Externalizing Behavior Problems. 
! Data from Achenbach Child Behavior Checklist of School Age Twins in Virginia.

G1: genetic structure
Data Calc NGroups=4
Matrices
A Lower 1 1 Free
Compute A*A' /
End

G2: specific environmental structure
Data Calc 
Matrices
E Lower 1 1 Free
Compute E*E' /
End

G3: Male MZ twins in larger families
Data NInput_vars=2 NObservations=171
Labels
exter1 exter2
CMatrix Symmetric
0.923
0.798 0.907
Matrices
A Symm 1 1 = %E1  
E Symm 1 1 = %E2
B Symm 2 2        ! sibling interaction parameters
I Iden 2 2
Covariances (I-B)~ *(A+E | A _
                     A   | A+E) *((I-B)~)' /
Specify B
0 3 0
Options RSidual
End 

G4: Male DZ twins in larger families
Data NInput_vars=2 NObservations=194
Labels
exter1 exter2
CMatrix Symmetric
0.671
0.448 0.700
Matrices
A Symm 1 1 = %E1
E Symm 1 1 = %E2
B Symm 2 2 = B3
H Full 1 1
I Iden 2 2
Covariances (I-B)~ *(A+E | H@A _
                     H@A | A+E) *((I-B)~)' /
Matrix H .5
Start .3 All
Start .0 B 3 2 1 B 4 2 1
Options NDecimals=4
Options RSidual
End