Variable System (VS) Program
Program Description
VS (Variable System) is a computer software program for the analysis of conditional path models based on structural equation modeling (SEM). It can be used to examine models with simple mediation, simple moderation, moderated mediation (moME), mediated moderation (meMO), and any combinations of them such as the one shown below:


VS runs on Windows environment together with the R system for statistical computing (R Development Core Team, 2015) that implements the package lavaan (Rosseel, 2012). In other words, you need to have R and the lavaan package installed on your PC in order to activate VS.

VS is easy to use. Users only need to specify the conceptual model using simple control languages in VS and the program will automatically (1) transform the conceptual model into a testable SEM-based model, (2) estimate the basic model parameters, (3) compute and test the conditional effects of interest, and (4) evaluate the model goodness-of-fit. 

Kwan, J. L.-Y., & Chan, W. (2017). Variable System: An alternative approach for the analysis of mediated moderation.  Psychological Methods.  Advance online publication. doi: 10.1037/met0000160

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