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Is it possible to test the moderating effect of M (M is a moderators which is subject to influence of N) on the path from X (independent variable) to Y (dependent variable). I think this will be a multilevel moderation on path from X to Y. (X>Y is moderated by N>M). Can you please guide me through the process? 


I don't understand your model. What role exactly does N play? What does "X>Y is moderated by N>M" mean? Why do you say it is multilevel? Please write out the full model in some way. 


HI, I am sorry I did not explain it well. You can see the visual representation of my model following the link http://postimg.org/image/g0ex0qvtr/. The model has 3 IVs (lets say A, B and C) and 1 DV (Z). The paths between IVs and DV is moderated my M and P. Moderator M is further influenced by N (e.g. M can represent 'trust' and N is 'trust determinant'). 


With a continuous moderator such as your M, you create interaction variables (products) in Define. So for instance am = a*m; Apart from that you simply say Z on ac am .... ; M on n; 


I used the DEFINE command but I have an error message 'undefined variable used in transformation' 


Please send the output and your license number to support@statmodel.com. 

Dan R. posted on Thursday, May 28, 2015  12:01 pm



For the time being, I've dropped the 111 mediation component from my model to first look at the level 2 moderation effect. My question is whether it looks like I set up my level 2 moderation effects (Y ON XW & Y ON MZ) appropriately (i.e., if these regressions are significant, can I claim level two moderation is supported). Here is the model with simplified variable names: Usevariables are Y X M W Z XW MZ; WITHIN = X M; BETWEEN = W Z; CLUSTER = Subject; DEFINE: XW=X*W; MZ=M*Z; Analysis: TYPE = TWOLEVEL; ESTIMATOR=MLR; Model: %WITHIN% Y ON X M; Y M; %BETWEEN% Y W Z XW MZ; Y ON W; Y ON XW; Y ON Z; Y ON MZ; Output: sampstat stdyx Tech1 Tech8; 


Looks ok so far. 

Dan R. posted on Thursday, May 28, 2015  8:39 pm



Thank you, Bengt. And for mediation tests at level 1 and level 2, have I set the following up correctly? Given the interaction effects, my understanding is that the overall chisquare and traditional fit statistics aren't available. So, should I report the BIC and SRMR for comparisons? I actually do get a Chisquare x(12)=6.213, but I'm not sure if this is for the overall multilevel model or just a portion of the model. Any insights you could provide would be greatly appreciated. Usevariables are Y X M W Z XW MZ; WITHIN = X M; BETWEEN = W Z; CLUSTER = Subject; DEFINE: XW=X*W; MZ=M*Z; Analysis: TYPE = TWOLEVEL; ESTIMATOR=MLR; Model: %WITHIN% Y ON X (cw); Y ON M (bw); M ON X (aw); Y M; %BETWEEN% Y W Z XW MZ; Y ON W; Y ON XW (cb); Y ON Z; Y ON MZ (bb); MZ ON XW (ab); MODEL CONSTRAINT: New(indirw directw totalw indirb directb totalb); indirw = aw*bw; directw = cw; totalw = cw+aw*bw; indirb = ab*bb; directb = cb; totalb = cb+ab*bb; Output: sampstat stdyx Tech1 Tech8; 


Your Between model looks strange. The "MZ" variable name sounds like an interaction term and it is not declared as Within or Between. 

Dan R. posted on Friday, May 29, 2015  12:21 pm



The MZ variable is an interaction  M is measured at level 1, and Z is measured at level 2. If I try to specify MZ on the between = line, I run into the following error: *** ERROR One or more betweenlevel variables have variation within a cluster for one or more clusters. Check your data and format statement. Between Cluster ID with variation in this variable Variable (only one cluster ID will be listed) AMG_NEGA 531 DLP_EF 531 Any thoughts? 


You typically don't have an interaction variable as a dependent variable as you do on Between saying MZ ON XW. MZ is not a betweenlevel variable given that M is measured on the within level. I don't see which kind of interaction model you are after for Between, that is, it isn't clear if you want to moderate the x>m, x>y, or m>y paths. Putting aside that you are doing this on Between for 2level model, maybe you want to study the Preacher et al (2007) MBR article on moderated mediation (singlelevel) to see how such interaction models are set up. 


Dear Dr. Muthen, I want to test whether L2 continuous variable (Z) moderates (inter=Z*X) the effects of L2 continuous variable X on changes in L1 dependent variable Y. 1. Is my syntax correct? If s on inter is significant does this suggest moderation? cluster = class id; within = wave0 Qwave; between = X Z inter; TYPE = COMPLEX TWOLEVEL RANDOM; MODEL: %within% s  Y ON wave0 Qwave; %between% Y; s ON X Z inter; 2. What is the difference in conclusions if I omit "random" and inter is significant (Y is measured at 3 time points)? TYPE = COMPLEX TWOLEVEL; MODEL: %within% Y; %between% Y; Y ON X Z inter; Thank you for your help. 


Approach 1. and 2. should be the same if the residual variance of s is zero. The s residual gets multiplied by the within predictor of Y. Note that your syntax for approach 1. has 2 predictors of Y on within  but you can only define a random slope for one at a time. Note also that if on Between you regress s on predictors, the same predictors typically influence Y as well. 


Dear Dr. Muthen, Thank you for your quick answer and guidance. Just to clarify, the "between" variances (L2) of both "S" and "Y" are significant for all 3 options of Random: %within% Y; option 1) S  Y ON wave; option 2) S  Y ON Qwave; option 3) S  Y ON wave Qwave; %between% Y; S; Should I go with approach 1. from my previous post to test moderation by L2 variable "Z" (inter=Z*X) of the effects of L2 variable "X" on changes in L1 variable "Y"? 


Yes, approach 1 is good but your input isn't correct. First, as I mentioned you cannot say s  Y ON wave0 Qwave; because the random slope statementrefers to one predictor, not two as you have. Second, on between you should let Y be regressed on X Z and inter. 


Dear Dr. Muthen, I want to run 211 multilevel moderation, please share the syntax. I am using 6.1 version of Mplus and unable to find any relevant syntax for 211 moderation.Thank you in advance. 


See our Mediation page at http://www.statmodel.com/Mediation.shtml under Preacher et al. multilevel mediation inputs 


Dear Dr. Muthen, I have few questions regarding multilevel moderation. First, can we test within and between level moderation? (e.g. Independent variables are based on between level and moderators are based on within level). Second, if so, which syntax are required to test multilevel moderation. I have not find any relevant syntax for my model in which independent variables (level 2) are based on between level and moderators and dependent variables are based on (level 1) within level. Thank you in advance. 


See our web page http://www.statmodel.com/Mediation.shtml under the heading Preacher et al. multilevel mediation inputs 

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