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Hi, I am using DSEM to analyse timeseries data of multiple participants. I look at the lagged associations, and the momentary associations (correlations between the residuals). I want to test whether the momentary association between X and Z differs significantly from X with Y. Is the following (simplified) approach correct? Model: %within% X with Z (a); X with Y (b); model constraint: new (test); test = ab; Does the significance of the "test" variable indeed indicate whether the association between xz is significantly different from xy? regards, Maurits 


It indicates the difference for the residual covariance, not the total covariance. 


How would I test the difference of the total covariance? Maurits 


You have to express the total variance and covariance in formulas based on your model using Model Constraint. 


I suspect that I may have specified the model correctly after all. To clarify: I specified a model with crosslagged effects and autocorrelation. The WithinLevel Standardized Estimates output also gives the output X WITH Y and X WITH Z. To my understanding they indicate the residual covariance. This residual covariance indicates the covariance after the lagged covoriances has been taken out (=estimate of momentary/contemporaneous covariance). If the above is correct, then shouldn't the following be correct to test whether the momentary covariances differ between XZ and XY? Model: %within% X with Z (a); !this indicates the residual covariance right? X with Y (b); model constraint: new (test); test = ab; !using absolute values I am having difficulties understanding why I would need the total covariance. 


The above test is for the residual covariance. If you want to test the total covariance you would need to use the formulas in Appendix D http://www.statmodel.com/download/DSEM.pdf These formulas are used in the computation of output:residual; 


Thank you for your reply. I do have a followup question. For the residual covariance, I report the withinperson standardized result. So I am interested in testing the difference in standardized coefficients instead of the unstandardized coefficients. For the newly created variable in model constraint, I only get unstandardized output. Is there a way to test the the difference between standardized coeffficients or would the test result be identical to the test for the unstandardized coefficients as I specified above? 


For the standardized test use this Model: %within% X with Z (a); X with Y (b); X (v1); Y (v2); Z (v3); model constraint: new (test); test = a/sqrt(v1*v3)b/sqrt(v1*v2); 


Thank you very much for your help, it is much appreciated! Maurits 

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