Mplus VERSION 8.8
MUTHEN & MUTHEN
04/19/2022 11:11 PM
INPUT INSTRUCTIONS
TITLE: this is an example of a two-group twin
model for continuous outcomes using parameter
constraints
DATA: FILE = ex5.21.dat;
VARIABLE: NAMES = y1 y2 g;
GROUPING = g(1=mz 2=dz);
MODEL: [y1-y2] (1);
y1-y2 (var);
y1 WITH y2 (covmz);
MODEL dz: y1 WITH y2 (covdz);
MODEL CONSTRAINT:
NEW(a c e h);
var = a**2 + c**2 + e**2;
covmz = a**2 + c**2;
covdz = 0.5*a**2 + c**2;
h = a**2/(a**2 + c**2 + e**2);
INPUT READING TERMINATED NORMALLY
this is an example of a two-group twin
model for continuous outcomes using parameter
constraints
SUMMARY OF ANALYSIS
Number of groups 2
Number of observations
Group MZ 1000
Group DZ 1000
Total sample size 2000
Number of dependent variables 2
Number of independent variables 0
Number of continuous latent variables 0
Observed dependent variables
Continuous
Y1 Y2
Variables with special functions
Grouping variable G
Estimator ML
Information matrix OBSERVED
Maximum number of iterations 1000
Convergence criterion 0.500D-04
Maximum number of steepest descent iterations 20
Input data file(s)
ex5.21.dat
Input data format FREE
UNIVARIATE SAMPLE STATISTICS
UNIVARIATE HIGHER-ORDER MOMENT DESCRIPTIVE STATISTICS FOR MZ
Variable/ Mean/ Skewness/ Minimum/ % with Percentiles
Sample Size Variance Kurtosis Maximum Min/Max 20%/60% 40%/80% Median
Y1 0.013 -0.062 -3.542 0.10% -0.800 -0.277 -0.009
1000.000 0.992 -0.153 3.057 0.10% 0.264 0.871
Y2 0.035 -0.019 -3.044 0.10% -0.850 -0.204 0.013
1000.000 1.055 -0.175 3.124 0.10% 0.314 0.929
UNIVARIATE HIGHER-ORDER MOMENT DESCRIPTIVE STATISTICS FOR DZ
Variable/ Mean/ Skewness/ Minimum/ % with Percentiles
Sample Size Variance Kurtosis Maximum Min/Max 20%/60% 40%/80% Median
Y1 -0.017 0.052 -2.675 0.10% -0.844 -0.251 -0.026
1000.000 0.984 -0.088 3.446 0.10% 0.202 0.823
Y2 0.006 0.091 -2.753 0.10% -0.846 -0.252 -0.026
1000.000 1.042 -0.059 2.969 0.10% 0.244 0.845
THE MODEL ESTIMATION TERMINATED NORMALLY
MODEL FIT INFORMATION
Number of Free Parameters 4
Loglikelihood
H0 Value -5216.004
H1 Value -5213.423
Information Criteria
Akaike (AIC) 10440.008
Bayesian (BIC) 10462.411
Sample-Size Adjusted BIC 10449.703
(n* = (n + 2) / 24)
Chi-Square Test of Model Fit
Value 5.161
Degrees of Freedom 6
P-Value 0.5233
Chi-Square Contribution From Each Group
MZ 3.443
DZ 1.718
RMSEA (Root Mean Square Error Of Approximation)
Estimate 0.000
90 Percent C.I. 0.000 0.038
Probability RMSEA <= .05 0.993
CFI/TLI
CFI 1.000
TLI 1.000
Chi-Square Test of Model Fit for the Baseline Model
Value 995.549
Degrees of Freedom 2
P-Value 0.0000
SRMR (Standardized Root Mean Square Residual)
Value 0.022
MODEL RESULTS
Two-Tailed
Estimate S.E. Est./S.E. P-Value
Group MZ
Y1 WITH
Y2 0.753 0.028 27.122 0.000
Means
Y1 0.008 0.020 0.395 0.693
Y2 0.008 0.020 0.395 0.693
Variances
Y1 1.018 0.026 38.648 0.000
Y2 1.018 0.026 38.648 0.000
Group DZ
Y1 WITH
Y2 0.432 0.031 13.992 0.000
Means
Y1 0.008 0.020 0.395 0.693
Y2 0.008 0.020 0.395 0.693
Variances
Y1 1.018 0.026 38.648 0.000
Y2 1.018 0.026 38.648 0.000
New/Additional Parameters
A 0.801 0.035 23.156 0.000
C 0.333 0.078 4.299 0.000
E 0.515 0.011 45.045 0.000
H 0.631 0.053 11.842 0.000
QUALITY OF NUMERICAL RESULTS
Condition Number for the Information Matrix 0.956E-04
(ratio of smallest to largest eigenvalue)
Beginning Time: 23:11:18
Ending Time: 23:11:18
Elapsed Time: 00:00:00
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