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The wild bootstrap was originally developed for regression models with heteroskedasticity of unknown form. Over the past 30 years, it has been extended to models estimated by instrumental variables and maximum likelihood and to ones where the error terms are (perhaps multiway) clustered. Like bootstrap methods in general, the wild bootstrap is especially useful when conventional inference methods are unreliable because large-sample assumptions do not hold. For example, there may be few clusters, few treated clusters, or weak instruments. The package boottest can perform a wide variety of wild bootstrap tests, often at remarkable speed. It can also invert these tests to construct confidence sets. As a postestimation command, boottest works after linear estimation commands, including regress, cnsreg, ivregress, ivreg2, areg, and reghdfe, as well as many estimation commands based on maximum likelihood. Although it is designed to perform the wild cluster bootstrap, boottest can also perform the ordinary (nonclustered) version. Wrappers offer classical Wald, score/Lagrange multiplier, and Anderson-Rubin tests, optionally with (multiway) clustering. We review the main ideas of the wild cluster bootstrap, offer tips for use, explain why it is particularly amenable to computational optimization, state the syntax of boottest, artest, scoretest, and waldtest, and present several empirical examples. [ABSTRACT FROM AUTHOR]

Extreme value theory models have found applications in myriad fields. Maximum likelihood (ML) is attractive for fitting the models because it is statistically efficient and flexible. However, in small samples, ML is biased to O(N-1) and some classical hypothesis tests suffer from size distortions. This paper derives the analytical Cox-Snell bias correction for the generalized extreme value (GEV) model, and for the model's extension to multiple order statistics (GEVr). Using simulations, the paper compares this correction to bootstrap-based bias corrections, for the generalized Pareto, GEV, and GEVr. It then compares eight approaches to inference with respect to primary parameters and extreme quantiles, some including corrections. The Cox-Snell correction is not markedly superior to bootstrap-based correction. The likelihood ratio test appears most accurately sized. The methods are applied to the distribution of geomagnetic storms. [ABSTRACT FROM AUTHOR]

Clemens, Radelet, Bhavnani, and Bazzi (CRBB) argue that the most-cited cross-country studies of the impact of foreign aid can be reconciled if changed in certain ways. The shared finding is then, in the CRBB view, that more aid is followed on average by more growth. I exactly replicate the estimation results of CRBB and then question these results with additional specifications and tests. One CRBB step, restricting the aid variable to assistance most likely to affect growth in the short run, does not make much difference. Two other changes—lagging the aid variables and differencing the data to remove fixed effects—fail to remove contemporaneous endogeneity. Addressing this issue produces evidence of zero or negative Granger causation from aid/(gross domestic product) to growth. And the regressions embodying all of CRBB’s changes do not peg the impact of aid as statistically significant. [ABSTRACT FROM PUBLISHER]

Multilevel multiprocess hazard models are routinely used by demographers to control for endogeneity and selection effects. These models consist of multilevel proportional hazards equations, and possibly probit equations, with correlated random effects. Although Stata currently lacks a specialized command for fitting systems of multilevel proportional hazards models, systems of seemingly unrelated lognormal survival models can be fit with the user-written cmp command (Roodman 2011, Stata Journal 11: 159-206). In this article, we describe multiprocess survival models and demonstrate theoretical and practical aspects of estimation. We also illustrate the application of the cmp command using examples related to demographic research. The examples use a dataset shipped with the statistical software aML. [ABSTRACT FROM AUTHOR]

We replicate and reanalyse the most influential study of microcredit impacts (M. M. Pitt & S. R. Khandker’s, ‘The impact of group-based credit on poor households in Bangladesh: Does the gender of participants matter?’, published in the Journal of Political Economy, 106, 1998). That study was celebrated for showing that microcredit reduces poverty, a much hoped for possibility (though one not confirmed by recent randomised controlled trials). We show that the original results on poverty reduction disappear after dropping outliers, or when using a robust linear estimator. Using a new program for estimation of mixed process maximum likelihood models, we show how assumptions critical for the original analysis, such as error normality, are contradicted by the data. We conclude that questions about impact cannot be answered in these data. [ABSTRACT FROM PUBLISHER]

We rank European countries' collective commitment to development on seven cross-border issues: aid, trade, investment, migration, environment, security and technology. We calculate a consolidated score for 21 European countries and show that they perform well on aid and environment but lag the rest of the world on trade and technology. We find that Europe's approach to development energetically tackles the symptoms of poor economic opportunities for developing countries by providing relatively effective aid, but there is an opportunity to do more to tackle the underlying structural causes of poverty. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The difference and system generalized method of moments (GMM) estimators are growing in popularity. As implemented in popular software, the estimators easily generate instruments that are numerous and, in system GMM, potentially suspect. A large instrument collection overfits endogenous variables even as it weakens the Hansen test of the instruments’ joint validity. This paper reviews the evidence on the effects of instrument proliferation, and describes and simulates simple ways to control it. It illustrates the dangers by replicating Forbes [ American Economic Review (2000) Vol. 90, pp. 869–887] on income inequality and Levine et al. [ Journal of Monetary Economics] (2000) Vol. 46, pp. 31–77] on financial sector development. Results in both papers appear driven by previously undetected endogeneity. [ABSTRACT FROM AUTHOR]

A challenge in the development of aggregate indexes of trade protection is weighting individual tariffs in ways that (a) reflect their importance and (b) are not endogenous to the protection being measured. The most obvious basis for weights is actual imports; but these may be highly endogenous. Various authors have worked to correct this endogeneity. For example, in the Bouët et al. (2004 ) ‘MAcMap’ data set, weights are based on imports of reference groups of countries. But eliminating the endogeneity is difficult in product areas where protection is high and widespread. I develop a new set of estimates of overall protection in rich countries with respect to developing ones that eschews import weights as much as possible in favour of weights based on the value of exporter's total production. The results are generally higher than those of Bouët et al. Product areas in which protection is high and widespread seem systematically de-emphasised when using MAcMap weights, especially in agriculture. I also estimate tariff equivalents of trade-distorting subsidies by country and commodity. Agricultural tariffs dominate subsidies in trade-distorting effect, and agricultural protection in turn dominates goods protection generally. Japan is most protective, largely because of rice tariffs near 900 per cent, followed by Norway and Switzerland. Because of their greater reliance on agriculture, the poorest countries face the highest barriers, despite tariff preferences. [ABSTRACT FROM AUTHOR]

The article provides information on Paget's disease of the bone. Both genetic and environmental factors appear to contribute to the etiology of the disease. Patients with this disease are often diagnosed with a combination of biochemical markers of bone turnover and radiological abnormalities. Since the osteoclast (OCL) is the primary cell affected by the disease, treatment is usually directed at inhibiting OCL formation or osteoclastic bone resorption, or inducing OCL apoptosis.

Provides an overview detailing the benefits of ecological tax reform. What ecological tax reform would include; Origin of ecological taxes; Implementation in the United States and Europe; Specifics on an ecological tax reform proposal; The need to phase in tax reforms gradually.

This article focuses on a previous research paper, which asserts that the evidence shows that aid works, in the sense of increasing growth. Having looked over the same literature, though perhaps somewhat less broadly than researchers of previous studies have, the author come to a different conclusion. Aid in general is not a decisive factor for economic growth and the studies look most at short-term effects over periods of only two to three years. It is a lot to expect of aid to have a clear effect on growth so rapidly.