Amos Reference Guide

856 Pages·2010·2.12 MB·English

IBM® SPSS® Amos(TM)
Amos 19 Reference
Guide
Amos Development Corporation

Prin ted on 15 July, 2010
Copyright 2010 James L. Arbuckle
i

Contents
New in Amos 19 1
Bootstrap for user-defined estimands............................................................................................................1
New in Amos 18 1
Improvements in the drawing of path diagrams............................................................................................1
Improvements to the Program Editor............................................................................................................1
Changes in the drawing of path diagrams.....................................................................................................2
Changes to the object model (for programmers)...........................................................................................2
New in Amos 17 1
Copy and paste path diagrams......................................................................................................................1
Convert a path diagram to a Visual Basic program......................................................................................1
Enhanced growth curve plugin.....................................................................................................................2
Specify a default value for the 'All groups' check box..................................................................................2
New PathDiagrammer method, EditPaste.....................................................................................................3
New PathDiagrammer method, ToolsWriteAProgram.................................................................................3
Changes to the Program................................................................................................................................3
New in Amos 16 5
Mixture Modeling.........................................................................................................................................5
Mixture Modeling, Clustering, and Discriminant Analysis..........................................................................5
Changes to the Program................................................................................................................................6
Programming with Amos 1
Getting Started..............................................................................................................................................2
Programming Tools......................................................................................................................................2
Writing a Main Program that Uses Amos.....................................................................................................3
Writing a Main Program with Amos's Built-in Editor.......................................................................3
Writing a Main Program with Visual Studio 2003............................................................................4
Writing Classes that are Used by Amos......................................................................................................12
Writing a Plugin for Amos Graphics...............................................................................................12
Calculating Custom Estimands........................................................................................................31
Class Reference...........................................................................................................................................31
Amos Graphics Class Reference......................................................................................................32
AmosEngine Class Reference........................................................................................................279
AmosMatrix Class Reference........................................................................................................651
AmosDebug Class Reference........................................................................................................667
AmosRanGen Class Reference......................................................................................................688
CAmosSeedManager Class Reference..........................................................................................732
CValue Class Reference................................................................................................................738
The t Namespace............................................................................................................................793
ii Contents

Additional Programming Examples..........................................................................................................811
Examples using the Amos Graphics classes..................................................................................811
Index 831
1

C HAPTE R 1
New in Amos 19
In This Chapter
Bootstrap for user-defined estimands................................1

Bootstrap for user-defined estimands
Amos 19 can estimate any function of the model parameters, complete with bootstrap standard errors,
confidence intervals and significance tests. You specify your own estimand (the quantity that you want to
estimate) by writing a program in Visual Basic or in C#. This is easier than it sounds. Typically, when you
want to estimate some new quantity, it is a very simple function of quantities that Amos already
calculates. For example, your estimand is likely to be the difference between two values that Amos
already calculates, or maybe a sum, a product or a ratio. In such cases, the program that you need to write
consists of a single line of code, along with some boilerplate code that Amos writes for you.
While a one-line program will often suffice, you have all the capability of a general-purpose language
(Visual Basic or C#) available when you need it This means that there are no limitations on what you can
estimate. Nothing stands in the way of estimating any computable function of the model parameters.
You can find some online videos that demonstrate user-defined estimands at
http://www.amosdevelopment.com/video/index.htm.

1

New in Amos 18
Improvements in the drawing of path diagrams
§ The appearance of path diagrams is improved.
§ The drawing interface is faster and more responsive.
§ Objects in path diagrams can be translucent with color gradients.
§ When variables in a path diagram are moved, all connecting arrows move simultaneously.
§ The magnifier tool (previously called the loupe tool) is improved.
§ You can open the Object Properties dialog by double-clicking an object in the path diagram. (Amos 5
had this capability. Now it is back.)

Improvements to the Program Editor
§ Classes and class members can be selected from dropdown lists.
§ Code completion in the Program Editor is improved.
§ The Program Editor displays helpful tooltips when the mouse is hovered over a token.
2 Amos 19 Reference Guide IBM® SPSS® Amos(TM)

Changes in the drawing of path diagrams
§ When path diagrams are copied to the clipboard, they are now copied as bitmaps, not as Windows
metafiles. The bitmap format has the drawback that the image of a path diagram becomes degraded
when you resize the image after pasting it into another application such as Microsoft Word.
§ In the list of path diagram files in the left pane of the path diagram window, you can click a file name
to open its path diagram. (It used to be a double-click.)
§ Context-sensitive help is now accessed in a consistent way throughout Amos Graphics. To obtain help
for an individual element (such as a button or a check box) of an Amos Graphics window, hold the
mouse pointer over that element and press F1.
§ The FillStyle (see "FillStyle Property" on page 217) property is ignored. It is retained for syntactic
compatibility with previous versions of Amos.
§ The four pen widths, very thin, thin, thick, very thick are no longer used.
§ The path diagram browser (formerly called the path diagram viewer) has been moved from the
Windows Start menu to the Amos Graphics File menu.
§ The Customize item has been removed from the Tools menu in Amos Graphics.

Changes to the object model (for programmers)
Variables of type Single are now of type Double.
Arguments to the AboutToShowMsgBox Event (on page 188) have changed.
The PathDiagrammer WindowHandle method has been eliminated.
The PathDiagrammer Form method has been replaced by the Window (see "Window Method" on page
185) method.
The PDElement Highlighted property has been renamed to IsHighlighted (see "IsHighlighted Property" on
page 223).
The PDElement Selected property has been renamed to IsSelected (see "IsSelected Property" on page
224).
1

New in Amos 17
Copy and paste path diagrams
You can copy and paste a path diagram, or part of a path diagram, from one Amos Graphics window to
another.
§ To copy a path diagram to the clipboard, click Editfi Copy (to clipboard).
§ To paste a path diagram from the clipboard to the Amos Graphics window, click Editfi Paste.

Convert a path diagram to a Visual Basic program
You can convert a path diagram to an equivalent Visual Basic program.
To convert a path diagram to a Visual Basic program, select Toolsfi Write a Program from the Amos
Graphics menu.
2 Amos 19 Reference Guide IBM® SPSS® Amos(TM)

Enhanced growth curve plugin
The growth curve plugin now automatically constrains parameters in a way that is appropriate for many
growth curve models. The following parameter constraints are imposed.
§ The regression weights for the "intercept" latent variable are fixed at 1.
§ The regression weights for the "slope" latent variable are fixed at equally spaced intervals starting at 0
and ending at 1. For example, if measurements were made at 5 time points, the 5 regression weights
are fixed at 0, 0.25, 0.50, 0.75 and 1.00.
§ The intercepts of the measured variables are fixed at zero.
§ The error variances are constrained to be equal by giving each error variance the same name, Var.
§ The error variables are required to be uncorrelated.
§ The means and variances of the "intercept" and "slope" latent variables are unconstrained.
§ The covariance between "intercept" and "slope" is unconstrained.
You can modify the parameter constraints after Amos draws the path diagram for the growth curve model.
For example, you will want to change the regression weights for the "slope" latent variable if your time
points are not equally spaced. If you want to remove the equality constraints on the error variances you
can do so by deleting the parameter name, Var, which is automatically assigned to all of the error
variances.
To use the growth curve plugin, click Pluginsfi Growth Curve Model.

Specify a default value for the 'All groups' check box
You can now specify a default value for the All groups check box. This allows you to choose whether the
path diagram objects that you draw will start out with a check mark next to All groups, or with no check
mark next to All groups. To specify a default value for the All groups check box:
1 In Amos Graphics, open or create a multiple-group model.
2 Draw a new object, say a rectangle.
3 Right-click the rectangle and then select Object Properties from the menu that pops up.
4 In the Object Properties dialog, click the Parameters tab.
5 Put a check mark next to All groups if you want the objects that you draw in the future to have All
groups checked by default. Or make sure that there is not a check mark next to All groups if you want
the objects that you draw in the future to have All groups unchecked by default.
6 Click the Set Default button.
7 In the Set Default Object Properties dialog, click OK.