By the definition of hidden variable (HVs); they are the parameters that determine what quantum states of two entangled particles will be after they are measured at particular measurement setups. Therefore and by definition, HVs should be reproducible and by undertaking measurements once or at any replica of times, the HVs could be estimated. For example, if u1 and u2 are two possible states of entangled particles, and a1 and a2 are two chosen measurements setups for measuring particle 1 and 2 respectively, then running the experiment once (or many times to avoid error) will let us know the HVs at this particular setups. So if the outcomes of the measurements come against what quantum mechanics predicts for certain combination of a1 and a1, then hidden variable theory is true. No need to have three measurements parameters like what are used in Bell`s inequality to validate the existence of hidden variables.