Interactive LISREL: User's Guide
Contents
1. Browse Since there are 2 latent variables Visual and Verbal the procedure outlined above for the observed variables is repeated by selecting Add List on the Latent Variables portion of the Labels dialog box Add varl var2 and click OK Assign labels to these latent variables by clicking on the number of each variable Finally click Next to go to the Data dialog box Observed Variables Latent Variables lt Previous CUBES LOZENGES Next gt Cancel HEL Add Read Variables Add Latent Variables Move Down Move Up Move Down Move Up 182 Data x Groups IF Same across groups r Summary statistics Statistics from File type Edit New Correlations z extemal ASCH Data E NEA I Fullmatrix 7 Fortran formatted File name Browse C isrel850 SPLEX E x5 cor mi Cancel Statistics included I Mean included in the data Summary Matrix W8igh Sy Number of observations T Include weight matrix 149 Matrix to be analyzed Weight filename _ Browse Correlations a Select Correlations from the Statistics from drop down list box and also Correlations from the Matrix to be analyzed drop down list box In the Number of Observations string field type 145 For File type select External ASCII Data and use the Browse button to locate exs cor in the splex folder Click OK when done 4 3 2 Drawing the Path Diagram We now proceed with the actual drawing of the path diagram S2. 177 Interactive LISREL User s Guide Mathilda du Toit Stephen du Toit pp 177 187 Scientific Software International Inc 4 3 Creating Syntax by Drawing Path Diagrams LISREL for Windows allows the user to create LISREL or SIMPLIS syntax by drawing the appropriate path diagram on the screen and then building the corresponding syntax directly from the path diagram This procedure will be demonstrated by fitting a CFA Confirmatory Factor Analysis model to the data To obtain correct standard errors of the estimators of the parameters the CFA model should be fitted to the observed covariance matrix However in order to illustrate how to build syntax from a path diagram the model will be fitted to the available correlation matrix In confirmatory factor analysis one builds a model assumed to describe or account for the empirical data in terms of relatively few parameters The model is based on a priori information about the data structure in the form of a specified theory or hypothesis or knowledge from previous studies based on extensive data Holzinger amp Swineford 1939 collected data on twenty six psychological tests administered to 145 seventh and eighth grade children in the Grant White school in Chicago Six of these tests were selected and for this example it was hypothesized that these measure two common factors visual perception and verbal ability such that the first 178 three variables measure visual perce
3. gBar Dption Object v Grid Lines CuhG Select the Title and Comments option from the Setup menu to obtain the Title and Comments dialog box Setup Draw View Image Ou Groups Variables Data The first item on the Title and Comments dialog box is the Title for the particular analysis Provision is also made for any additional Comments that the user may wish to enter After typing in the title and optionally the comments click on Next to go to the Group Names dialog box Title and Comments Title Confirmatory factor analysis with 6 variables Comments Next gt Subset of the 9 variables in the SIMPLIS language guide Since the present example is based on the analysis of one correlation matrix nothing is entered in the space allowed for Group Labels and Next is clicked to go to the Labels dialog box The default number of variables shown on the Labels dialog box is 2 these being VAR 1 and VAR 2 181 Since we have six observed variables the Add Read Variables option is selected On the Add Read Variables dialog box of which the top half is shown below check the Add list of variables radio button Enter the labels VIS PERC CUBES WORDMEAN one by one in the Var List field Note that a label name which may include blanks may not exceed 8 characters Add Read Variables x Read from file fosReL System File z Add list of variables e g varl var5 Var List VIS PER
4. ght mouse button The menu shown below will appear on the draw part of the screen Select the Align gt Left option Once this is done select the Even Space gt Vertically option One can alternatively use the Align option on the Zmage menu to achieve this Note that the alignment of objects is not really necessary Once syntax is built from the path diagram and the program is run a properly aligned path diagram is displayed VIS PERC ft n CUBES r Zoom Rotate EvenSpace gt Right QB e 2118 oO o in Size Top m Options Bottom Grid Lines m z Q a va VIS PERC Q m S fol ig amp m o a 5 5 Q e ISEN COMI ORDME BE 185 The rectangular objects will now be aligned and one can proceed by dragging the latent variables Visual and Verbal to the path diagram window Note that latent variables are represented by elliptically shaped objects 0 00007 VIS PERC 0 0000 0 0000 LOZENGES 0 0000 0 0000 5EN COMP 0 0000 WORDMEAN CUBES il AR COMP i Finally arrows can be drawn pointing from the latent variables to the observed variables To accomplish this click on the single headed arrow of the Draw toolbar seen on the right of the picture given below and move the mouse pointer to within one of the elliptically shaped objects With the left mouse button held down drag the arr
5. gram In the Save As dialog box select a filename and a folder in which the path diagram should be saved For the present example the folder chosen is splex and the file name selected is cfa6 pth When done click Save From the Output menu select SIMPLIS Outputs The dialog box below will appear Customize this dialog box according to your preferences For example change the Number of Decimals in the Output option to 4 Make sure that the Invoke Path Diagram check box the default is checked When done click OK SIMPLIS Outputs Ea Method of Estimation C Generalized Least Squares C Two stage Least Squares C Generally Weighted Least Squares C Instrument Variables C Unweighted Least Squares C Diagonally Weighted Least Squares I Set Check Admissibility to 20 Iterations Maximum Number of Iterations 1 Number of Decimals 0 8 in the Output I Print Residuals I Wide Print I Save Sigma fitted matrix sis I Crossvalidate File cv Cancel Default Help IP Select LISREL Outputs Invoke Path Diagram Before drawing the path diagram select Toolbars from the View menu and ensure that the items shown below are selected These are Toolbar Status Bar Typebar Variables Drawing Bar Optionally also check the Grid Lines option 180 Image Output Window Help Toobar Groups gt v Status Bar Model Types gt v Typebar Estimations gt v Variables Se Sees i Options v Drawin
6. ow to within a rectangular shaped object When the colors of both objects change see diagram below release the mouse button Note that the Draw menu on the main menu bar can also be used when drawing path diagrams Related draw tool options are contained in this menu 2 o 0 0000 CUBES 0 0000 LOZENGEG 0 0000 PAR COMP 0 0000 Proceed in a similar fashion to graphically display the relationships between the observed and latent variables as shown on the next image 186 Select the Build SIMPLIS Syntax option from the Setup menu SIMPLIS syntax not shown below will be built from the path diagram and is stored in a system file named cfa6 spj Click the Run LISREL icon button to fit the CFA model to the data Parameter estimates are shown on the path diagram given below 0 617 0 713 0 6186 1 0 5358 o a500 EBEE o 7288 2 0099 0 5332 a 1 0006 0 8261 o oo BA 0 22 l 0 3151 Chi Square 4 37 df 8 P value 0 82193 RMSEA 0 000 By altering the path diagram model specifications may be changed The covariance between Visual and Verbal may for example be fixed by clicking right mouse button 187 on the two headed arrow representing this covariance This will enable the pop up menu shown below Select the Fix option using the left mouse button Click the Run LISREL icon button to fit the revised CFA model to the data The path diagram x fit statistic and RMSEA a
7. ption and the last three measure verbal ability The six selected variables and their intercorrelations are given below VIS PERC 1 000 CUBES 0 318 1 000 LOZENGES 0 436 0 419 1 000 PAR COMP 0 335 0 234 0 323 1 000 SEN COMP 0 304 0 157 0 283 0 722 1 000 WORDMEAN 0 326 0 195 0 350 0 714 0 685 1 000 The path diagram for this model is given below 0 617 VIS PERC R 0 7130 cuers fw c 0 4688 LOZENGES 0 7288 0 2aase PAR COMP d i 0 3176 SEN COMP Pa 0 3156 WORDMEAN Chi Square 4 37 df 8 P value 0 82193 RMSEA 0 000 The corresponding SIMPLIS syntax file is Six Psychological Variables A Confirmatory Factor Analysis Observed variables VIS PERC CUBES LOZENGES PAR COMP SEN COMP WORDMEAN Correlation Matrix From File EX5 COR Sample Size 145 Latent Variables Visual Verbal Relationships VIS PERC LOZENGES Visual PAR COMP WORDMEAN Verbal Number of decimals 4 Print Residuals End of Problem 179 Some important aspects contained in the SIMPLIS syntax file given above are e The correlation matrix is read from an external file e There are two latent variables in the model Visual and Verbal e The statement Number of decimals 4 specifies that we wish to have the results in the output file given to an accuracy of four decimals LISREL uses two decimals by default 4 3 1 Title Labels and Data Select the File New option and click on Path Dia
8. re shown below 0 6186 0 7131 N 0 5358 i 1 00 0 5332 0 2445 PAO 0 269 1 0000 0 8261 ose oss 0 315 l Chi Square 4 37 df 9 P value 0 88514 RMSEA 0 000
9. tart by clicking on the VIS PERC label under the Observed variables portion of the Labels window Hold the mouse button down and drag the label to the draw area indicated by the grid lines A rectangular shaped object will appear on this part of the screen when the mouse button is released as shown below Note also that e The observed variables are assumed to be X or independent variables unless appropriate squares under the Y column are clicked e The latent variables are assumed to be KSI or independent variables unless appropriate squares under the Eta column are clicked 183 Observed Y Confirrnatory factor analysis 6 E CUBES P LOZENGE PAR COMI SEN COMI WORDME Latent _ Eta Visual fe Verbal je Repeat the same procedure for each of the remaining 5 variables by clicking on a label left mouse button and dragging the object to the draw area on the screen The result of these operations should look similar to the image given below VIS PERC H UBES i LOZENGES Latent_ Eta Visual a Verbal E SEN COMI ORDME mm The rectangles representing the six observed variables can be properly aligned by going through the following steps e Choose Select all from the Edit menu or draw a rectangle with the mouse pointer around all the objects to be included 184 e Move the mouse pointer to the vicinity of the selected objects and click the ri
Download Pdf Manuals
Related Search