Dear all,
I have a question regarding using an implied covariance matrix as an input in addition to a sample covariance matrix with the tetrad macro.
More precisely, I don’t know how to input an implied covariance matrix in addition to a sample covariance matrix in order to carry out a tetrad analysis using ssd.
I am using the matrixes given by Bauldry and Bollen for simplicity.
Thanks to help on the forum I am able to run tetrad analysis with only the sample covariance matrix as input using ssd :
clear all
ssd init x1 x2 x3 x4 x5 x6
ssd set obs 2000
ssd set cov (ltd) 1 .490 .490 .448 .098 .098 .490 1 .490 .448 .098 .098 .490 .490 1 .448 .098 .098 .448 .448 .448 1 .560 .560 .098 .098 .098 .560 1 .490 .098 .098 .098 .560 .490 1
. qui sem (X1-> x1 x2 x3 x4 x5 x6)
. qui estat framework, fitted
. mat sigma1 = r(Sigma)
. tetrad x1 x2 x3 x4 x5 x6, icm1(sigma1) reps(5) tlist (1)
I do not know, however how to input the implied covariance matrix hereunder as an implied covariance using ssd :
1 .490 .490 .448 .098 .098 .490 1 .490 .448 .098 .098 .490 .490 1 .448 .098 .098 .448 .448 .448 1 .560 .560 .098 .098 .098 .560 1 .490 .098 .098 .098 .560 .490 1
Could someone help me in how to input the implied covariance matrix. Many thanks in advande for your help.
In their article Bauldry and Bollen give the following matrixes (h = the sample covmat and a= the implied covmat) :
mat sigma_h = (1.000, 0.490, 0.490, 0.098, 0.098, 0.098 \ ///
0.490, 1.000, 0.490, 0.098, 0.098, 0.098 \ ///
0.490, 0.490, 1.000, 0.098, 0.098, 0.098 \ ///
0.098, 0.098, 0.098, 1.000, 0.490, 0.490 \ ///
0.098, 0.098, 0.098, 0.490, 1.000, 0.490 \ ///
0.098, 0.098, 0.098, 0.490, 0.490, 1.000)
mat colnames sigma_h = x1 x2 x3 x4 x5 x6
mat rownames sigma_h = x1 x2 x3 x4 x5 x6
mat sigma_a = (1.000, 0.490, 0.490, 0.448, 0.098, 0.098 \ ///
0.490, 1.000, 0.490, 0.448, 0.098, 0.098 \ ///
0.490, 0.490, 1.000, 0.448, 0.098, 0.098 \ //
/0.448, 0.448, 0.448, 1.000, 0.560, 0.560 \ ///
0.098, 0.098, 0.098, 0.560, 1.000, 0.490 \ ///
0.098, 0.098, 0.098, 0.560, 0.490, 1.000)
mat colnames sigma_a = x1 x2 x3 x4 x5 x6
mat rownames sigma_a = x1 x2 x3 x4 x5 x6
. tetrad_matrix, scm(sigma_a) icm1(sigma_h) obs(100)
I have a question regarding using an implied covariance matrix as an input in addition to a sample covariance matrix with the tetrad macro.
More precisely, I don’t know how to input an implied covariance matrix in addition to a sample covariance matrix in order to carry out a tetrad analysis using ssd.
I am using the matrixes given by Bauldry and Bollen for simplicity.
Thanks to help on the forum I am able to run tetrad analysis with only the sample covariance matrix as input using ssd :
clear all
ssd init x1 x2 x3 x4 x5 x6
ssd set obs 2000
ssd set cov (ltd) 1 .490 .490 .448 .098 .098 .490 1 .490 .448 .098 .098 .490 .490 1 .448 .098 .098 .448 .448 .448 1 .560 .560 .098 .098 .098 .560 1 .490 .098 .098 .098 .560 .490 1
. qui sem (X1-> x1 x2 x3 x4 x5 x6)
. qui estat framework, fitted
. mat sigma1 = r(Sigma)
. tetrad x1 x2 x3 x4 x5 x6, icm1(sigma1) reps(5) tlist (1)
I do not know, however how to input the implied covariance matrix hereunder as an implied covariance using ssd :
1 .490 .490 .448 .098 .098 .490 1 .490 .448 .098 .098 .490 .490 1 .448 .098 .098 .448 .448 .448 1 .560 .560 .098 .098 .098 .560 1 .490 .098 .098 .098 .560 .490 1
Could someone help me in how to input the implied covariance matrix. Many thanks in advande for your help.
In their article Bauldry and Bollen give the following matrixes (h = the sample covmat and a= the implied covmat) :
mat sigma_h = (1.000, 0.490, 0.490, 0.098, 0.098, 0.098 \ ///
0.490, 1.000, 0.490, 0.098, 0.098, 0.098 \ ///
0.490, 0.490, 1.000, 0.098, 0.098, 0.098 \ ///
0.098, 0.098, 0.098, 1.000, 0.490, 0.490 \ ///
0.098, 0.098, 0.098, 0.490, 1.000, 0.490 \ ///
0.098, 0.098, 0.098, 0.490, 0.490, 1.000)
mat colnames sigma_h = x1 x2 x3 x4 x5 x6
mat rownames sigma_h = x1 x2 x3 x4 x5 x6
mat sigma_a = (1.000, 0.490, 0.490, 0.448, 0.098, 0.098 \ ///
0.490, 1.000, 0.490, 0.448, 0.098, 0.098 \ ///
0.490, 0.490, 1.000, 0.448, 0.098, 0.098 \ //
/0.448, 0.448, 0.448, 1.000, 0.560, 0.560 \ ///
0.098, 0.098, 0.098, 0.560, 1.000, 0.490 \ ///
0.098, 0.098, 0.098, 0.560, 0.490, 1.000)
mat colnames sigma_a = x1 x2 x3 x4 x5 x6
mat rownames sigma_a = x1 x2 x3 x4 x5 x6
. tetrad_matrix, scm(sigma_a) icm1(sigma_h) obs(100)
