Does ensemble interpretation of QM involve hidden variables? The ensemble interpretation of quantum mechanics considers the quantum state description to apply only to an ensemble of similarly prepared systems, rather than supposing that it exhaustively represents an individual physical system. (Wikipedia).
But ensembles involve many similar but different systems. What else but systems with different hidden variables may quantum ensemble include?
 A: The ensemble interpretation is just a handwaving, even compared to other fuzzy interpretations. In fact, it is not so much an interpretation as a refusal to interpret. Thus, it is difficult to answer any meaningful deep question about this interpretation, including the hidden variables one.
A: I think ensemble interpretation assumes that the wavefunction describes behaviour of a system of particles called ensemble. This is not exactly ensemble as the term is used in statistical physics which led be to confusion. The purpose is to avoid strange things like particle interfering with itself. we consider only interference of different particles. I think this is clever idea but physics experiment now with individual partiles so the future of ensemble interpretation is not clear.
A: The ensemble interpretation of quantum mechanics has some problems related to the question you asked.
If we take quantum mechanics as being an accurate description of reality, then systems are similarly prepared if they have the same quantum state. And we have explanations of how to produce systems in quantum states and what is happening in reality in quantum mechanical experiments. Attempts to perform experiments can then be judged by coming up with explanations of how to check whether the experiment has been set up correctly.
Advocates of the ensemble interpretation don't say what is happening in reality to produce the results predicted by quantum mechanics, so they have no way of specifying what it means for systems to be identically prepared. Nor do they have any means of saying whether an experiment has been performed correctly since they have no description of what is happening in the experiment. So the ensemble interpretation can't be used to perform or interpret experiments, which is a problem for a theory that claims to be an interpretation.
As for hidden variables, since no theory of hidden variables exists, it doesn't make much sense to speculate about what such a theory would predict. Also, the advocates of the ensemble interpretation would ignore any such theory since they don't want to say anything about how the world actually works.
