Fixed , Random , or Something in Between ? A Variant of HAUSMAN ’ s Specifi cation Test for Panel Data Estimators

This paper proposes a variant of the classical HAUSMAN specifi cation test commonly employed to decide whether the estimation of a random-eff ects model is a viable alternative to estimating fi xed eff ects. Whereas the classical test probes the equality of fi xedand random eff ects, the proposed variant focuses on the equality of between-groups and fi xed-eff ects coeffi cients. While both test procedures lead to the same conclusions, the panel model specifi cation underlying our testing strategy facilitates the simultaneous estimation of the fi xedand between-groups eff ects. As a consequence, we are able to examine both the equality of the whole range of coeffi cients as well as that of individual variables. The usefulness of the test is illustrated using a panel of household travel data for Germany. JEL Classifi cation: C12