An Open Source Structural Equation Modeling Graph Drawing Application
Student: Doug Scheurich
Supervisor: J. Edmonds
Structural equation modeling (SEM) is a statistical technique that is becoming increasingly popular in the sciences. SEM allows researchers to test the validity of hypothesized models involving complex relationships among multiple variables. These models can include latent variables, which are not measured directly but are constructs inferred by observed variables. Structural equation models can be represented visually by graphs. To generate such graphs currently in R would require over 80 lines of code which has no reusability and has to be re written each time a new graph has to be developed or analyzed (R is a UNIX based command line only program, however it is a very powerful analytic research tool).
Collected data is used to estimate the parameters of the equations and assessing the fit of the model. There are several SEM software options available to researchers, however all have serious limitations (Windows only, Unix only, expensive licensing fees, text based or command line only, no GUI, etc).
We propose developing an application which will allow the user to load observed variables from a data file to create graphs, or allow using an intuitive graphical interface, and convert the graphs into a text based model specification file (ie generate the code required so the graph can be used in other programs such as R). This text file can then be used as input for the sem() function in R. The application will be implemented in Java, which can then be used with any OS. Later versions may include the ability to call R functions directly from within the application and provide options for more advanced structural equation modeling techniques.