IBM® SPSS® Amos™ 28

By default, Amos assumes that there are no constraints on the variances of the exogenous variables in the model. However, you can constrain the variances, as in the following example:

    Dim Sem as New AmosEngine
    . . .
    Sem.AStructure("variable1 (gamma)")
    Sem.AStructure("variable2 (gamma)")
    Sem.AStructure("variable3 (gamma)")
    Sem.AStructure("variable4 (1)")
    Sem.AStructure("variable5 (2)")
    Sem.AStructure("variable6 (delta)")
    Sem.AStructure("variable7 (delta)")
    . . .

In this example, the variance of variable4 is fixed at 1, and the variance of variable5 is fixed at 2. Amos does not attempt to estimate these fixed parameters. variable1, variable2 and variable3 are required to have the same variance because they are all labeled gamma. Similarly, variable6 and variable7 are required to have the same variance because they are both labeled delta.