The Calculus of M-estimation in R with geex

M-estimation, or estimating equation, methods are widely applicable for point estimation and asymptotic inference. In this paper, we present an R package that can find roots and compute the empirical sandwich variance estimator for any set of user-specified, unbiased estimating equations. Examples from the M-estimation primer by Stefanski and Boos (2002) demonstrate use of the software. The package also includes a framework for finite sample variance corrections and a website with an extensive collection of tutorials

Federal Tax Rulings: Procedure and Policy

The rulings program of the Internal Revenue Service was designed to meet the need for predictability of the tax consequences of any given financial transaction. Though the rulings program is not particularly important to the average taxpayer, it has become increasingly crucial both to the financial community and to the Service itself. As the tax laws become more complex, and tax risks become increasingly important to the success of business ventures, the need for confirmation before entering into a transaction is intensified. Thus parties to a transaction will generally request a ruling... whenever the answer is uncertain or when the transaction involves substantial sums of money, even when the uncertainty may not be very great. In such circumstances the availability of a ruling in advance of the transaction has become almost as important as the financing or the know-how involved. This note will study the growth of the rulings program, the factors which must be weighed by the tax practitioner before requesting a ruling, and the amount of reliance which the taxpayer can safely place upon the Service\u27s interpretation of the law as applied to his particular fact situation

Synchronization in the presence of distributed delays

We study systems of identical coupled oscillators introducing a distribution of delay times in the coupling. For arbitrary network topologies, we show that the frequency and stability of the fully synchronized states depend only on the mean of the delay distribution. However, synchronization dynamics is sensitive to the shape of the distribution. In the presence of coupling delays, the synchronization rate can be maximal for a specific value of the coupling strength.Comment: 6 pages, 3 figure

The fish fauna of the Iwokrama Forest

Fishes were collected from the rivers in and around the Iwokrama Forest during January-February and November-December 1997. Four hundred species of fish were recorded from forty families in ten orders. Many of these fishes are newly recorded from Guyana and several are thought to be endemic. The number of species recorded for the area is surprising given the low level of effort and suggests that this area may be particularly important from a fish diversity perspective. This paper focuses on species of particular interest from a management perspective including those considered economically important, rare or endangered. The paper is also the basis for developing fisheries management systems in the Iwokrama Forest and Rupununi Wetlands