Creating and Editing PLS Model

　

A data file must be prepared before the creating of PLS model. The requirement for a legitimate data file was discussed in the previous section. Then the following steps are detailed in squence:

1.Click File|New Model or click button to create a new PLS Project. The default file type is vpl. PLS code will be written into this file. You need to finish these steps to create a valid PLS code file:

Step 1: Specifying PLS Project File Name.

Step 2: Locating data file.

o       The data type is raw data. The default extension name is txt or dat.

o       Once the PLS project is created, the data file cannot be changed.

　

Step 3: Building the measurement model.

 All the indicators will be read from the first row in the data file and listed in the manifest variable list box. The indicators will  be removed when they are assigned to a latent variable.

Step 4: Constructing the structural model.

The path model can be created by dragging lines between constructs.

Step 5: Specifying model parameters.

Open PLS Project

click the button to open PLS Project.

Select Cases

Select Cases provides methods for selecting a subgroup of cases based on criteria that include variables and expressions.

Model Building

　

All the indicators will be read from the first row in the data file and listed in the manifest variable list box, shown in the left part of the window.

　

New Construct

 Constructs must be created before assigning manifest variables. Three operations are related to managing latent variables.

o       New Construct: By clicking the Tool/New Construct or  button, then click on the canvas in the proper position, you can create a new construct.

o       Delete Construct: Highlight a latent variable and click Delete to remove it. The associated manifest variables will be released.

o       Rename: To rename a latent variable, double-click it in the construct. A dialog window will pop up to accept a new name. You need to follow the naming rules described above to add a valid variable name.

Assign indicators to construct

You can assign manifest variables after adding new constructs. Just double-click on the

construct, the associated Indicators and Constructs window will show up. To assign

indicators to this construct, just select the un-used indicators (shown in the left list box)

and click the Assign button. Multiple selections are supported. The associated manifest

variables will move to the right part. If you want to release indicator (s) associated with a

construct, and select the indicator (s) you will release in the right list box, then click

Remove button. Click OK button, the manifest variable list box will display the

relationship between indicators and constructs.

Note: You can specify the direction of the manifest variable, either Reflective or Formative .

　

Constructing the path model

The path model can be created by drawing arrow-lines between variables.  To add paths

between constructs, press the button, then click the the independent variables and drag to the dependent variables.  To remove a path, just click on the path and press the [DEL] key , or right-click the mouse button, select Delete Path to remove the path..

Specifying model parameters.

Default parameters are pre-set and estimate the model with general constraints and produce commonly used results. You can make changes to these parameters by selecting items from the parameter lists, or by filling in parameter boxes. It is recommended not to change them unless you are familiar with the meaning of the parameters. If you have made any changes and want to restore the settings, click Reset. The parameters for a correlation matrix model and a raw data model are different. The following is a list of both sets of parameters. Please read the help file in Lvpls package (pls.hlp) for details.

Calculation of Stone-Geisser Q2:

        to estimate the Q2 coefficients, the type of blindfolding static and Blindfolding omission distance in no. of cases must be selected.

Save Model

You can save the current model by clicking Save Model.

Save As

You can save the current model under another name by clicking Save As.

　

Formative v.s. Reflective Indicators

Formative and reflective are represented in both windows, as depicted in the picture below.

　

Executing the Model Estimate and Model Confirmation

　

Run Model Estimation

To execute the PLS code, click Execute|Run PLS or click the button. If there are no

parameter to estimate, or incomplete configuration (for example, a construct with no indicator

assigned to it), the model estimation process will stop and inform the user. It may take a few

minutes to run the model if your sample size is very large. please be patient. the progress bar

shows the current status during the execution.

　

Model Confirmation

Significance test was conducted using re-sampling procedure. Both bootstrap and jackknife were

provided in VisualPLS.

Run the bootstrap procedure

To execute the bootstrap procedure, click Execute|Run bootstrap or click the button.

Depending on the re-sampling number, model size, and your computer speed, it may take several

minutes to finish the procedure. The progress bar shows the current status during the execution.

Run the jackknife procedure

To execute the bootstrap procedure, click Execute|Run jackknife or click the button.

Depending on the re-sampling number, model size, and your computer speed, it may take several

minutes to finish the procedure. The progress bar shows the current status during the execution.

Interactoin Effects and Moderators

Partial Least Squares Product Indicator Approach

The Product indicator approach, proposed by Chin(1996), was support in the VisualPLS. The predictor (X) and moderator (Z) indicators are used to create product indicators by creating all possible products from the two sets of indicators. These product terms are used to reflect the latent interaction variable. For example, if the predictor (X) has three indicators and the moderator variable (Y) has 2 indicators, as graphically depicted below, we would have six measures for representing the construct of interaction effect (X*Z).

Step to Model Interaction Effects with VisualPLS

Step 1: Generate Product Terms for Interaction Effects

Step 2: Create a Construct for Interaction Effect

Step 3: Assign product Indicators to Constructs

　

How to   generate Product Terms for Interaction Effects

Click the Button, then select [New product terms (for interaction)]

If you want to generate product terms using existing construct, then select [Constructs] button, else select [Indicators] button

Press [Constructs] Button

the [Generate Product Terms from Constructs] window appear. The user then select predictor construct and moderator variable to generate product terms. Be sure to assign 2-character Alias for predictor and moderator variable to generate indicator name for products terms.

Press [OK] button, then these product terms will show up in the manifest variable list box.

Press [Indicators] Button

the [Generate Product Terms from Individiau items] window appear. The user then select predictor indicator and moderator indicator to generate a product term, one at a time. Be sure to assign 3-character Alias for predictor and moderator variable to generate indicator name for products terms.

Change/Delete Product Terms

Then generated product term can be deleted or changed. The Filter box will help user to list indicators related to a specific construct to ease the management of multiple product indicators.