use the relationship investment theory on studying a variety of physical-product and service brands, and in general confirm its predictability of brand loyalty. In contrast to the commitment-trust model, the relationship investment model does not include relationship trust as an exogenous construct. Besides, it concentrates more on the cognitive aspect of commitment. Apparently, the researchers of the relationship investment model tend to accentuate the calculative nature of relationship commitment, which is determined by calculating the financial resources, cognitive efforts and time invested in the relationship as well as the attractiveness of the current relational partner in comparison to other possible alternatives.