Furthermore, from a statistical perspective, the addition of independent variables to a regression often improves the explanatory power of a model. For these reasons, multifactor models relax the assumption and constraint of a single risk factor and look for other factors that affect expected return to assets.
As a result of the many hypotheses regarding various risk factors, and the abundance of data available regarding publicly traded stocks, a great deal of research has been performed with the goal of identifying additional risk factors that have robust predictive capability.