Technical Aspects of Drawing AMOS Models

Now that we're beginning to learn how to draw models in AMOS (which, by the way, stands for Analysis of Moment Structures), I thought I'd list some of the technical aspects you'll see in the program. Most of the time, AMOS implements these technical aspects automatically, but it's important you know what is going on. [Update, Feb. 12: I've just added a diagram below to help illustrate the following principles; you can enlarge the diagram by clicking directly on it.]

1. Every manifest indicator (box) or latent construct (big circle) that has an incoming unidirectional "causal" arrow gets a residual (or error) term (small circle).

2. Every manifest indicator and latent construct (like any ordinary variable) gets a variance. If the indicator or construct has no incoming unidirectional arrow, its variance is located in the indicator or construct itself. However, if something has a residual, the variance is located only in the residual.

3. Non-directional, "curved" correlations can be inserted only between two entities that have variances. Thus, if two entities each have residual variances, it is the residual variances that get correlated, not the indicators or constructs themselves.