underidentified

The songs are laughably underidentified, and not a single text is included.

Thus the system is underidentified.

If there is too little information available on which to base the parameter estimates, then the model is said to be underidentified, and model parameters cannot be estimated appropriately.

The parameters are underidentified (equivalently, not identified) if there are fewer instruments than there are covariates or, equivalently, if there are fewer excluded instruments than there are endogenous covariates in the equation of interest.