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I'm designing a weekly diary study to assess alcohol consumption and severity of conflict situations with approx 28 time points. I'm interested in capturing the between as well as within person correlations between these two variables. I want to use LGM but I am not expecting any meaningful trajectory across time point but variation and significant within person correlations. I understand how this would be implemented in HLM (although not using latent variables) using Random Coefficient Regression model with Level 1 showing the within person correlations but would like to use a latent procedure. Can you tell me which model would be appropriate in Mplus. Thank you. 


You can do it the way that HLM does it in Mplus. But if you want to use latent variables, you would estimate an intercept only model for each outcome. The variances of the intercept growth factors would capture between variance and individual variance would be captured in the residual variances of the outcomes. 


Would I regress one intercept growth factor on the other. I assume this would give me the between individual correlation but I'm not sure where I would get the within individual correlations (would it be by correlating the residuals for the observed variables at each time point?)Thanks. 


You should correlate the two intercept growth factors. This is the default if they are exogenous variables. 


I asked a while back about the possibility of calculating withinindividual correlations in MPLUS. I am conducting some LGMs of weekly depression scores and weekly alcohol consumption scores. So far I have 13 consecutive weeks. I also want to look at the relationships between depression and alcohol. I understand that I could do this using LGM for two parallel processes and investigate the correlation between the growth factors for depression and alcohol. Given that I have (weekly) diary data I would like to be able to look not only at the between individual correlation between depression and alcohol but also the withinindividual correlations. I have read that these two types of correlations can differ substantially. I understand that this is standard in HLM but I would like to use Mplus if possible. Is there a procedure in MPLUS that would provide the mean (and variance) of the withinindividual correlation between depression and alcohol. Thank you. 


I'm not sure exactly what you want. Can you either write out the HLM model for what you want or send an HLM output that shows what you want to support@statmodel.com.? 

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