The paper derives a general Central Limit Theorem (CLT) and asymptotic distributions for sample moments related to panel data models with large n. The results allow for the data to be cross sectionally dependent, while at the same time allowing the regressors to be only sequentially rather than strictly exogenous. The setup is sufficiently general to accommodate situations where cross sectional...

We point out that the theory of difference fields with algebraically closed fixed field has no model companion. By a difference field we mean a field K equipped with an automorphism σ. It is well-known ([?]) that the class of existentially closed difference fields is an elementary class (ACFA), and moreover all completions are unstable. The fixed field (set of a ∈ K such that σ(a) = a) is respo...

introduction: a study model is a precise three dimensional replica of patient’s dentition and plays an important role in treatment planning. many digital multi-media applications have become available to the clinician and his or her staff to facilitate standard procedures in practice and management. the aim of this study is to evaluate reliability and validity of dental measurement made on digi...