We give a non-technical introduction to convergence-divergence models, a new modeling approach for phylogenetic data that allows for the usual divergence of species post speciation but also allows for species to converge, i.e. become more similar over time. By examining the 3-taxon case in some detail we illustrate that phylogeneticists have been “spoiled” in the sense of not having to think ab...

This paper investigates the impact of instructional days on student performance. Because school year length is endogenously determined, I estimate the causal impact of school year length through two quasi-experiments that exploit different sources of variation in instructional days. The first identifies school year length’s effect through weather-related cancellations in Colorado and Maryland. ...

This paper provides a selective survey of the panel macroeconometric techniques that focus on controlling the impact of “unobserved heterogeneity” across individuals and over time to obtain valid inference for “structures” that are common across individuals and over time. We consider issues of (i) estimating vector autoregressive models; (ii) testing of unit root or cointegration; (iii) statist...

The general linear group acts on m-tuples of N ×N matrices by simultaneous conjugation. Quantum deformations of the corresponding rings of invariants and the so-called trace rings are investigated. 2000 Mathematics Subject Classification. 16W35, 16R30, 20G42

This paper investigates whether codependence restrictions can be uniquely imposed on VAR and VEC models via the so-called pseudo-structural form used in the literature. Codependence of order q is given if a linear combination of autocorrelated variables eliminates the serial correlation after q lags. Importantly, maximum likelihood estimation and likelihood ratio testing are only possible if th...

A new way of constructing efficient semiparametric instrumental variable estimators is proposed. The method involves the combination of a large number of possibly inefficient estimators rather than combining the instruments into an optimal instrument function. The consistency and asymptotic normality is established for a class of estimators that are linear combinations of a set of √ n– consiste...

defined on n-tuples of commuting elements of G and invariant under simultaneous conjugation. Thus, in [HKR00] the study of nth Morava E-theory at a prime p leads to χ(g1, ..., gn) defined on gi of p-power order. On the other hand, the construction of equivariant elliptic cohomology in [Dev96] (which corresponds to n = 2) uses functions χ(g1, g2) as above but without restrictions on the order. T...

This paper deals with loan contracting from a private bank in Vietnam. We focus on the main loan contract features that the bank uses in lending to business firms, namely loan maturity, collateral and loan interest rate. Based upon the simultaneous equation model of Dennis et al. (2000) and the bank’s loan contracting policies, we examine the possible interdependency of the three different loan...

in this paper we introduce a sequential block iterative method and its simultaneous version with op-timal combination of weights (instead of convex combination) for solving convex feasibility problems.when the intersection of the given family of convex sets is nonempty, it is shown that any sequencegenerated by the given algorithms converges to a feasible point. additionally for linear feasibil...