Correlations from ADE and AE, huge differences

Hi all,

I am writing this post since I am fitting an ADE bivariate model, but I get really different correlations from the ADE and the AE model.

Here you can see the correlations for both models:

> fitADE$algebras$VC
mxAlgebra 'VC'
$formula: cbind(A, D, E, A/V, D/V, E/V)
$result:
A A D D E E SA SA SD
VC 0.060119702 0.086110014 0.028546937 -0.051261209 0.171507340 0.051611766 0.23107500 0.99594547 0.10972249
VC 0.086110014 0.123336193 -0.051261209 0.111217434 0.051611766 0.409801824 0.99594547 0.19141018 -0.59288539
SD SE SE
VC -0.59288539 0.65920251 0.59693991
VC 0.17260261 0.59693991 0.63598721

> mxEval(cov2cor(MZ.expCovMZ), fitADE, T)
[,1] [,2] [,3] [,4]
[1,] 1.000000000 0.211165720 0.340797490 0.085112473
[2,] 0.211165720 1.000000000 0.085112473 0.364012792
[3,] 0.340797490 0.085112473 1.000000000 0.211165720
[4,] 0.085112473 0.364012792 0.211165720 1.000000000

> mxEval(cov2cor(DZ.expCovDZ), fitADE, T)
[,1] [,2] [,3] [,4]
[1,] 1.000000000 0.211165720 0.142968122 0.073855504
[2,] 0.211165720 1.000000000 0.073855504 0.138855743
[3,] 0.142968122 0.073855504 1.000000000 0.211165720
[4,] 0.073855504 0.138855743 0.211165720 1.000000000

> fitAE$algebras$VC
mxAlgebra 'VC'
$formula: cbind(A, D, E, A/V, D/V, E/V)
$result:
A A D D E E SA SA SD SD SE
VC 0.049583546 0.089029836 0 0 0.2104231076 -0.0016801462 0.19070107 1.01923471 0 0 0.809298933
VC 0.089029836 0.159857711 0 0 -0.0016801462 0.4835435673 1.01923471 0.24845725 0 0 -0.019234713
SE
VC -0.019234713
VC 0.751542752

> mxEval(cov2cor(MZ.expCovMZ), fitAE, T)
[,1] [,2] [,3] [,4]
[1,] 1.00000000 0.21356406 0.19070107 0.21767191
[2,] 0.21356406 1.00000000 0.21767191 0.24845725
[3,] 0.19070107 0.21767191 1.00000000 0.21356406
[4,] 0.21767191 0.24845725 0.21356406 1.00000000

> mxEval(cov2cor(DZ.expCovDZ), fitAE, T)
[,1] [,2] [,3] [,4]
[1,] 1.000000000 0.21356406 0.095350533 0.10883595
[2,] 0.213564064 1.00000000 0.108835954 0.12422862
[3,] 0.095350533 0.10883595 1.000000000 0.21356406
[4,] 0.108835954 0.12422862 0.213564064 1.00000000
>

As you can see there are huge differences between the ADE and AE correlations. In the ADE model the cross-twin cross-trait correlation is almost equal for MZ and DZ whereas in the AE model there is a notable difference (MZ=0.22; DZ=0.11) I do not know why I am getting so different correlations. What should I do?

Thank you so much in advance!

With all good wishes,