! Scalar Sex-Limitation Model
! BMI data in US twins

G1: model parameters
Data Calc NGroups=6
Begin Matrices;
X Lower 1 1 Free    ! genetic structure
Z Lower 1 1 Free    ! specific environmental structure
W Lower 1 1 Free    ! dominance structure
H Full 1 1
Q Full 1 1 
End Matrices;
Matrix H .5
Matrix Q .25
Begin Algebra;
A= X*X' ;
E= Z*Z' ;
D= W*W' ;
End Algebra;
End

G2: Female MZ twin pairs
Data NInput_vars=2 NObservations=1802
Labels bmi_t1 bmi-t2
CMatrix Symmetric File=usbmimzf.cov
Matrices= Group 1
Covariances A+D+E | A+D _
            A+D   | A+D+E /
Option RSidual
End 

G3: Female DZ twin pairs
Data NInput_vars=2 NObservations=1142
Labels bmi_t1 bmi-t2
CMatrix Symmetric File=usbmidzf.cov
Matrices= Group 1
Covariances A+D+E   | H@A+Q@D _
            H@A+Q@D | A+D+E /
Option RSidual
End

G4: Male MZ twin pairs
Data NInput_vars=2 NObservations=750
Labels bmi_t1 bmi-t2
CMatrix Symmetric File=usbmimzm.cov
Matrices= Group 1
K Diag 2 2        ! common multiplier
Covariances K *(A+D+E | A+D _
                A+D   | A+D+E) *K' /
Specify K 4 4
Option RSidual
End 

G5: Male DZ twin pairs
Data NInput_vars=2 NObservations=553
Labels bmi_t1 bmi-t2
CMatrix Symmetric File=usbmidzm.cov
Matrices= Group 1
K Diag 2 2 = K4
Covariances K *(A+D+E   | H@A+Q@D _
                H@A+Q@D | A+D+E) *K' /
Option RSidual
End

G6: Female-Male DZ twin pairs
Data NInput_vars=2 NObservations=1341
Labels bmi_t1 bmi-t2
CMatrix Symmetric File=usbmidzo.cov
Matrices= Group 1
K Diag 2 2 
Covariances K *(A+D+E   | H@A+Q@D _
                H@A+Q@D | A+D+E) *K' /
Specify K 0 4
Matrix K 1 0
Bound 0 1 K 4 1 1 K 4 2 2 K 5 1 1 K 5 2 2 K 6 2 2
Start .7 All
Option RSidual
Options NDecimals=4
End