IBM® SPSS® Amos™ 28
Specifies a covariance as a model parameter.
Syntax
object.Cov (leftVariableName, rightVariableName)
object.Cov (leftVariableName, rightVariableName, parameterValue)
object.Cov (leftVariableName, rightVariableName, parameterName)
The Cov method syntax has the following parts:
Part |
Description |
object |
An object of type AmosEngine. |
leftVariableName rightVariableName |
The character strings, leftVariableName and rightVariableName, are the names of two exogenous variables. The Cov method makes their covariance a model parameter. |
parameterValue |
(Optional) Parameter value. If parameterValue = 3, say, then the covariance is fixed at 3. |
parameterName |
(Optional) Parameter name. If parameterName = "abc", say, then the covariance is named "abc". It is constrained to be equal to any other parameters named "abc". If parameterName = "3?", say then the covariance is given an initial value of 3, and is unconstrained. If parameterName = "abc:3", say, then the covariance is named "abc" and is given an initial value of 3. It is constrained to be equal to any other parameters named "abc". If parameterName is an empty string (""), the covariance is an unconstrained parameter. |
Placement: [2].
Default
With one exception, Amos assumes that the exogenous variables in a model are correlated, and it estimates the covariance between every pair of exogenous variables. The exception to this default assumption concerns unique variables - exogenous variables that are unobserved and have a direct effect on only one variable. Amos assumes that unique variables are uncorrelated with each other, and with every other exogenous variable in the model.
You can modify these defaults with the GenerateDefaultCovariances method.
Remarks
If parameterValue and parameterName are omitted, the covariance is an unconstrained parameter.
See Also
