That is, there must be discriminant validity . In the structural model , there are a set of structural equations. The causal variables are called exogenous variables and the effect variable is called the endogenous variable . Unexplained variation is referred to as disturbance . Minimum Condition of Identifiability Let k be the number of constructs in the structural model .
Theory places restrictions on a.
If a structural model satisfies this condition, then the model may be identified. Although there is no known proof of this condition, there is no known exception. It seems likely that the rule holds. As with any identification rule, the model may still not be empirically identified . This rule considers models that fail to meet the previous rule, but may still be identified.