This paper proposes new simple testing procedures for the joint null hypothesis of absence of persistent e®ects in the form of random e®ects and ¯rst order serial correlation in the error component model. The fact that the presence of random effects is clearly of a one-sided nature, together...

This paper shows that the standard Newey-West GMM based test is sensitive to the presence of locally misspecified alternatives. In particular, such test is shown to have incorrect size when the null model is locally contaminated, making the test spuriously reject the null hypothesis even when it...

An additivity property of LM tests is derived, linking joint, marginal and Bera-Yoon `adjusted' tests, hence the latter can be derived as the difference of the first two. An artificial regression framework provides an intuitive geometrical illustration of the Bera-Yoon principle.