LISREL is a statistical software package developed by Karl Jöreskog and Dag Sörbom. It is used for the estimation of LInear Structural RELationships and for many other types of multivariate analysis, such as factor analysis, multiple regression, path analysis, analysis of mean structure and multisample analysis.
The LISREL model in its most general form consists of two
parts: the measurement model and the structural equation model.
The measurement model specifies how latent variables or hypothetical constructs depend upon or are indicated by the observed variables. It describes the measurement properties (reliabilities and validities) of the observed variables.
The structural equation model specifies the casual relationships among the latent variables, describes causal effects, and assigns the explained and unexplained variance.
LISREL 8.3 contains the command language SIMPLIS, which uses plain English input commands. The LISREL package also includes PRELIS 2, a program for multivariate data screening and data summarization, which can be used as a preprocessor for LISREL.
IMPORTANT POINTS TO REMEMBER:
- Project files must be run from c:\temp or d:\temp or an external drive (floppy drive a:\ or zip drive).
- Keep all files related to a project, such as covariance and correlation matrices, in the same directory as the project.
To Start LISREL
Click on the LISREL 8.3 icon in the Applications folder.
Building a LISREL Project Interactively
The LISREL for Windows program allows the user to build a LISREL project interactively by making use of a set of menus. The project is stored as LISREL system data (*.lpj), which may later be loaded and modified. A project is also associated with its own set of syntax (*.ls8), output (*.out), path diagram (*.pth) and matrix files.
- Click on File / New / LISREL project
Select a filename and a folder in which the LISREL project should be saved. Click OK when done.
NOTE: Remember to run projects from c:\temp or d:\temp or an external drive (floppy drive a:\ or zip drive).
- The project begins with the Setup Menu, which includes submenus for Title, Comments, Variables and Data. Click on the Next button to proceed through the stages of the project. Note: If you click on OK, you will be returned to the main project window, but previous input information will retained. Follow the instructions on the bottom of each window to input information.
- Click on Setup / Title to input optional Title and Comments for the project. Click on Next to proceed.
- Group Labels: if the analysis consists of a single group, leave blank and click on Next to proceed. For multi-group analyses, fill in group labels. Add groups using the insert key.
Labels: specify labels for observed and latent variables. Add single variables using the insert key or the down-arrow key. To add lists of variables (ex. var1-var5), click on Additional Variables. Note: a label name, which may include blank spaces, may not exceed 8 characters.
- Data: specify information on the data to be analyzed, including the type (statistics from: item), name and location of the external file, as well as weights, if any, number of observations and matrix to be analyzed.
- The next set of commands are found within the Model Menu
- Define Observed Variables: select (or remove) Y and X variables.
- Define Latent Variables: specify eta and ksi variables.
- Model Parameters: check the Model Summary items for correct specifications. Modify specifications by highlighting particular matrices and changing the matrix type and mode, if necessary. To fix or free particular parameters, highlight the matrix and click on Specify to invoke the Elements and Values window. Fix or Free elements as needed. To set the values for fixed parameters, type in the value in the particular cell.
- Constraints: specify constraints across parameters. Start from the left with EQ (equality), IR(interval restrictiont), or CO (linear and non-linear constraints). Highlight the matrix and double click on the particular elements for which constraints are to be imposed.
Examples: EQ TD(1,1) TD(2,2) TD(3,3)
IR TD(2,2) > 0
IR GA(2,4) <1
IR PH(2,1) >-1 <1
CO LX(1,4)=LX(1,5) - LX(1,6)**4
- The final set of commands are found in the Output menu
- Estimations: click on the type of estimation desired.
- Selections: click on the output desired. Also click on Invoke Path Diagram to generate a path diagram for the model.
- Save Matrices: Click on the matrices to be saved. Each matrix saved has its own extension, and you can specify your own filename. If you do not provide your own filenames for the selected matrices, they will be saved with the same filename as the project. This is the last submenu in the project.
Example: for a project model1, the lambda-y matrix, if selected, will be saved, by default, as model1.lys
- Whenever any of the menus above are exited (click on OK), LISREL automatically builds and modifies the syntax and displays it in the project window.
- To run the LISREL program lines, click on the Run LISREL icon (with the L) on the toolbar.
- When the program lines are executed, an output window/file (*.out) is invoked and has the same filename as the project. Also invoked is a path diagram (if option is checked in the Selections menu).
The output can be converted to rich text format (RTF) or to a *.TEX file: click on File / Save As.
Modifying a LISREL Project
Project specifications may be modified through the appropriate submenus. Click on Next to advance to the next menu, if necessary, or click on OK to exit the menus. The modifications should be applied and displayed in the current project window.
Using the Path Diagram
If the program is successfully executed, the Path Diagram window is invoked (assuming this option was checked in the Selections window). One may modify the path diagram by deleting, fixing or adding paths.
- Make the Path Diagram window the current window
- Click on Draw and choose the path/correlation desired. Click on the starting variable/error term and drag the cursor to the other variable/error term. A path should be drawn between the points.
- To generate new estimates with deleted and/or added paths, click on the Run LISREL icon. The new estimates will be shown in the path window.
- To modify the syntax with the new path specifications, click on Setup / Build LISREL Syntax. Note: this will replace the syntax of the current project. To save modifications as a new project, build syntax and click on File / Save As and provide new file specifications.
Building a LISREL Project
Using an External Syntax File
Users can also utilize an external LISREL syntax file to build a LISREL project.
- Click on File / New / LISREL Project to begin writing a new project.
- Copy and Paste the contents of the syntax file to the project window
- Click on Setup / Initialize: this step will use the syntax pasted into the project window as specifications for the new project. Run the command lines or make additional modifications as desired.
Online Help is available
- Click on Help / Index for an introduction and tutorial
- Click on Help / Index / Search to look up specific commands
- Other Resources
- The Form of Structural Equation Models
- SEMNET The Structural Equation Modeling Discussion Network (discussion group and FAQ).
lm: June 28, 1999