OverviewOverview

Introduction to AMOS User Interface AMOS Graphics

Examples of using AMOS Predictors of Problem Drinking using

Path analysis

SEM SoftwareSEM Software Several different packages exist EQS, LISREL, MPLUS, AMOS AMOS, SAS, ...

Provide simultaneouslysimultaneously overall tests of model fit individual parameter estimate tests

May compare simultaneouslysimultaneously Regression coefficients Means Variances

even across multiple between-subjects groupseven across multiple between-subjects groups

AMOS AdvantagesAMOS Advantages

Easy to use for visual SEMvisual SEM ( Structural Equation Modeling). Easy to modify, viewmodify, view the modelPublication –quality graphicsgraphics

Structural Equation Modeling Structural Equation Modeling (SEM) (SEM)

An extension of Regression and general Linear Models

Also can fit more complex models, like confirmatory factor analysis and longitudinal data.

Family Tree of SEMFamily Tree of SEMT-test

ANOVAMulti-wayANOVA Repeated

MeasureDesigns Growth

CurveAnalysis

BivariateCorrelation

MultipleRegression

PathAnalysis

StructuralEquationModeling

FactorAnalysis

ExploratoryFactor

Analysis

ConfirmatoryFactor

Analysis

LatentLatentGrowthGrowthCurveCurve

AnalysisAnalysis

Structural Equation Modeling Structural Equation Modeling (SEM)(SEM)

Observed variables =measuredmeasured

Latent variables=unobservedunobserved

ExogenousExogenous

variables=independentindependent

Endogenous variables

=dependentdependent

Structural Equation Structural Equation GraphsGraphs

Observed Observed VariableVariable

LatentLatentVariableVariable

.15

ErrorError

: Loading Loading

.10 : RR22

Example: Condom Use Example: Condom Use ModelModel

Gender

Peer norms about condoms

Condom use

Impulsive Decision Making

IDMC1R

Observed Variables

Latent Variables

.15 Loadings

LegendLegend

IDMA1R IDME1R IDMJ1R

Impulsive Decision Making

Observed variables for Impulsive decision making

Condom attitude

Example: Condom Use Example: Condom Use ModelModel

IDMC1R

Observed Variables

Latent Variables

.15 Loadings

LegendLegend

IDMA1R IDME1R IDMJ1R

Independent

Dependent

DependentDependent

Independent

Dependent

Gender

Peer norms about condoms

Condom use

Impulsive Decision Making

Condom attitude

Example: Condom Use Example: Condom Use ModelModel

eSXYRC1

efr1

eiss

IDMC1R

eidm4eidm2eidm2eidm1

Observed Variables

Latent Variables

.15 Loadings

LegendLegend

IDMA1R IDME1R IDMJ1R

Gender

Peer norms about condoms

Condom use

Impulsive Decision Making

Condom attitude

Example: Condom Use Example: Condom Use ModelModel

SEX1

eSXYRC1

efr1

eiss

IDMC1R

eidm4eidm2eidm2eidm1

Observed Variables

Latent Variables

.15 Loadings

LegendLegend

IDMA1R IDME1R IDMJ1R

Gender

Peer norms about condoms

Condom use

Impulsive Decision Making

Condom attitude

Example: Condom Use Example: Condom Use ModelModel

eSXYRC1

efr1

eiss

IDMC1R

eidm4eidm2eidm2eidm1

Observed Variables

Latent Variables

.15 Loadings

LegendLegend

IDMA1R IDME1R IDMJ1R

.11.38

-.06

-.10-.19

-.15 .13

.53.49 .69 .67

.15

.05

.28 .24 .48 .45

.03

Gender

Peer norms about condoms

Condom use

Impulsive Decision Making

Condom attitude

AMOS ComponentsAMOS Components

AMOS GraphicsAMOS Graphics draw SEM graphsgraphs runs SEM models using graphs

AMOS Basic runs SEM models using syntax

Starting AMOS GraphicsStarting AMOS Graphics

Start Programs Amos 6 Amos Graphics

Reading Data into AMOS

FileFile Data FilesData Files The following dialog appears:

Reading Data into AMOSClick on File NameFile Name to specify the name of the data file Currently AMOS reads the following

data file formats:  Access dBase 3 – 5 Microsft Excel 3, 4, 5, and 97 FoxPro 2.0, 2.5 and 2.6 Lotus wk1, wk3, and wk4 SPSSSPSS *.sav files*.sav files, versions 7.0.2 through 15.0 (both raw data and matrix formats)

Reading Data into AMOS

Example USED today: Predicting parental monitoring and Predicting parental monitoring and

problem drinking using a PATH DIAGRAM.problem drinking using a PATH DIAGRAM.

DATASET: only_valid_path_feb19_2007-n754.sav

this file is in the “DROP” folder on desktop

Drawing in AMOSIn Amos Graphics, a model can be specified by drawing a diagram on the screen 1. To draw an observed variable, click

"Diagram" on the top menu, and click "Draw ObservedDraw Observed." Move the cursor to the place where you want to place an observed variable and click your mouse. Drag the box in order to adjust the size of the box. You can also use     in the tool box to draw observed variables.

  2. Unobserved variables can be drawn similarly. Click "Diagram" and "Draw UnobservedDraw Unobserved." Unobserved variables are shown as circles. You may also use      in the toolbox to draw unobserved variables.

Drawing in AMOSDrawing in AMOSTo draw a path, Click “DiagramDiagram” on the top

menu and click “Draw PathDraw Path”. Instead of using the top menu, you may use the Tool Box buttons to draw arrows ( and ).

Drawing in AMOSTo draw Error Term to the observed and unobserved variables. Use “Unique VariableUnique Variable” button in the Tool Box. Click and then click a box or a circle to which you want to add errors or a unique variables.(When you use "Unique Variable" button, the path coefficient will be automatically constrained to 1.)

Drawing in AMOSLet us draw:

Naming the variables in Naming the variables in AMOSAMOSTo name a variable, Click “View” on the top menu and click “Object Properties”Object Properties”

•Click on the box you want to name

Click on the TextText tab and enter the name of the variable in the Variable Variable namename field and /or Variable Label

Naming the variables in AMOS

Example: Name the variables

Constraining a parameter in AMOSConstraining a parameter in AMOS

The scale of the latent variable or variance of the latent variable has to be fixed to 1.

Click “Object PropertiesObject Properties“,

then on the arrow between PRNTMNT1 and eprnt.

Click on the ParametersParameters tab and enter the value “11” in the Regression weightRegression weight field:

Improving the appearance Improving the appearance of the path diagramof the path diagram

You can change the appearance of your path diagram by moving objects aroundTo move an object, click on the MoveMove icon on the toolbar. You will notice that the picture of a little moving truck appears below your mouse pointer when you move into the drawing area. This lets you know the MoveMove function is active. Then click and hold down your left mouse button on the object you wish to move. With the mouse button still depressed, move the object to where you want it, and let go of your mouse button. Amos GraphicsAmos Graphics will automatically redraw all connecting arrows.

Improving the appearance of the Improving the appearance of the path diagrampath diagram

To change the size and shape of an object, first press the Change the shape of objectsChange the shape of objects icon on the toolbar. You will notice that appears under the mouse pointer to let you know the ShapeShape function is active. Click and hold down your left mouse buttonleft mouse button on the object you wish to re-shape. Change the shape of the object to your liking and release the mouse button.Change the shape of objectsChange the shape of objects also works on two-headed arrows. Follow the same procedure to change the direction or arc of any double-headed arrow.

Improving the appearance of the path diagram

If you make a mistakemake a mistake, there are always three icons on the toolbar to quickly bail you out: the EraseErase and UndoUndo functions.

To erase an objecterase an object, simply click on the EraseErase icon and then click on the object you wish to erase.

To undo your last drawing activityundo your last drawing activity, click on the UndoUndo icon and your last activity disappears.Each time you click Undo,Undo, your previous activity will be removed.

If you change your mindIf you change your mind, click on RedoRedo to restore a change.

Performing the Performing the analysis in AMOS analysis in AMOS

ViewViewAnalysis Analysis PropertiesProperties and click on the Output Output tab.

There is also an Analysis PropertiesAnalysis Properties icon you can click on the toolbar. Either way, the OutputOutput tab gives you the following options:

Performing the analysis in AMOS

For our example, check the Minimization Minimization history, Standardized estimateshistory, Standardized estimates, and Squared Squared multiple correlationsmultiple correlations boxes. (We are doing this because these are so commonly used in analysis).

To run AMOSAMOS, click on the Calculate estimatesCalculate estimates icon on the toolbar. AMOSAMOS will want to save this problem to a file. if you have given it no filename, the Save AsSave As

dialog box will appear. Give the problem a file name; let us say, tutorial1tutorial1:

Results Results When AMOSAMOS has completed the calculations, you have two options for viewing the output:

text outputtext output, graphics outputgraphics output.

For text output, click the View Text View Text Output Output icon on the toolbar.

Here is a portion of the text output for this problem:

The model is recursive. Sample size = 754The model is recursive. Sample size = 754Chi-square=Chi-square=49.98449.984 Degrees of Freedom =9Degrees of Freedom =9Maximum Likelihood EstimatesMaximum Likelihood Estimates

Results for Path Model

Regression Weights: (Group number 1 - Default model)

Standardized Regression Weights: (Group number 1 - Default model)

Standardized Regression Weights: (Group number 1 - Default model)

Viewing the graphics output in AMOSViewing the graphics output in AMOS

• To view the graphics output, click the View outputView output icon next to the drawing area.

• Chose to view either unstandardizedunstandardized or (if you selected this option) standardizedstandardized estimates by click one or the other in the Parameter FormatsParameter Formats panel next to your drawing area:

Unstandardized path model

Improving the appearance of the path Improving the appearance of the path diagramdiagram

To move the parameters, click on the “Move Parameter values” and then click on the path, and move the parameter

Conclusion: Amos In nutshell

Today we learned ONE thing:how to draw a model in AMOS

Topics for the next few weeks : assess and interpret the models compare models analyze more complex models