1. 1 A Latent Variable Model

2. 2 Grace & Keeley 2006 Ecol Apps Example: Observed Variable Model

3. 3 How do we create a latent variable? (1) First, use this tool to draw an ellipse, representing a latent variable. (2) To name it, right click on the ellipse, select “object properties”, and name it “Land”.

4. 4 How do we create a latent variable? (cont.) (3) Select this tool and click it on Land once to create a single indicator. (4) You can open and drag from the list of variables the variable coastran, which is our indicator for Land. (5) Remember, you still need to name the error for coastran! default weight from latent to indicator is set at 1 for single indicator. path from error to indicator set to 1.

5. 5 How do we create a latent variable? (cont.) (6) Keep in mind that if a latent variable is endogenous, it will need its own error variable (Le1 in this case).

6. 6 Grace & Keeley 2006 Example with Latent Variables We are now modeling interactions among latent variables. Each LV has an indicator and each indicator has an error. Endogenous LVs have prediction errors. Indicator errors have been set to zero (i.e., there is no measurement error).

7. 7 Grace & Keeley 2006 Example w/ LVs - Results Results are identical to those from the observed variable model.

8. 8 Grace & Keeley 2006 Example with Measurement Error Measurement error specified in raw units.

9. 9 Grace & Keeley 2006 Example with ME - Results

10. 10 Comparison of Results Can you find the main differences?