A statistical uncertainty principle for estimating the time of a discrete shift in the mean of a continuous time random process

The purpose of this article is to present a statistical uncertainty principle that can be used when localizing a single change in the mean of a band-limited stationary random process. The statistical model investigated is a continuous time process that experiences a shift in its mean. This continuous time process is presumed to be sampled using an ideal low-pass filter. The least squares estimate of the location of the change in mean is asymptotically Gaussian. The standard deviation of the least squares estimate of the location of the change-point provides a physical limit to the accuracy of the estimate of the time of the mean shift which cannot be bettered.     

The Foster–Greer–Thorbecke (FGT) poverty measures: 25 years later

Twenty-five years ago, the FGT class of decomposable poverty measures was introduced in Foster, Greer, and Thorbecke (Econometrica 52:761–776, 1984). The present study provides a retrospective view of the FGT paper and the subsequent literature, as well as a brief discussion of future directions. We identify three categories of contributions: to measurement, to axiomatics, and to application. A representative subset of the literature generated by the FGT methodology is discussed and grouped according to this taxonomy. We show how the FGT paper has played a central role in several thriving literatures and has contributed to the design, implementation, and evaluation of prominent development programs; the breadth of its impact is evidenced by the many topics beyond poverty to which its methodology has been applied. We conclude with a selection of prospective research topics.     

Political Distrust and Social Capital in Europe and the USA

Levels of rising political distrust in the USA and parts of Europe attracted political scientists’ attention in the 1990s, and urged them to look at possible consequences of this phenomenon for the functioning of democracies and social life. Approximately during the same period, from a sociological viewpoint, social capital theorists started studying the effects of declining social capital on political and economic life. In this article, we looked at the relationship between political distrust and social capital from an interdisciplinary perspective. We studied the relationship in six European countries from three regions (North-West, South and East), and the USA, and we were interested in the question of whether this relationship varies over the regions, or whether it is approximately the same everywhere. We used ISPP data from the 2004 wave, which included a range of social capital indicators and political distrust items. Social capital was subdivided into four dimensions, namely, networks (membership of organizations), interpersonal or social trust, social norms (citizenship norms), and linking social capital (political activities). First we studied the effect of political distrust on these four dimensions of social capital, while controlling for other variables such as political efficacy, political interest and a set of socio-structural background variables. One of our main findings was that the only significant effect of political distrust we found throughout all countries was a negative effect on one dimension of social capital, namely, interpersonal trust: the more people distrust politicians and people in government, the less they trust other people in general, even when controlled for all other variables. The reverse relationship led us to the same conclusion: the more people tend to trust people in general, the less they distrust politics, a result we found in all countries. This finding refutes the claim that there is no or either only a very weak relationship between political and social trust, as some have strongly argued before. Other important political attitudes connected to social capital were political interest and political efficacy, and for political distrust it was external efficacy. Significant socio-economic factors were religiousness and educational level for membership of voluntary organizations, educational level for interpersonal trust, religiousness for citizenship norms, and educational level and age for political activities. The reciprocal relationship was strongest in the USA and North-Western Europe, as were the explained variances of our (more extensive) regression models. In Southern and Eastern Europe other factors appear to be at work which influence both social capital and political distrust.     

ESTIMATION, PREDICTION AND INFERENCE FOR THE LASSO RANDOM EFFECTS MODEL

The least absolute shrinkage and selection operator (LASSO) can be formulated as a random effects model with an associated variance parameter that can be estimated with other components of variance. In this paper, estimation of the variance parameters is performed by means of an approximation to the marginal likelihood of the observed outcomes. The approximation is based on an alternative but equivalent formulation of the LASSO random effects model. Predictions can be made using point summaries of the predictive distribution of the random effects given the data with the parameters set to their estimated values. The standard LASSO method uses the mode of this distribution as the predictor. It is not the only choice, and a number of other possibilities are defined and empirically assessed in this article. The predictive mode is competitive with the predictive mean (best predictor), but no single predictor performs best across in all situations. Inference for the LASSO random effects is performed using predictive probability statements, which are more appropriate under the random effects formulation than tests of hypothesis.     

Response to symposium on Artifacts and Allegiances: How Museums Put the Nation and the World on Display

The author responds to the contributions to this symposium, highlighting her ideas about diversity management regimes, the urban cultural armature, global museum assemblages, the cosmopolitan-nationalism continuum, and new methods for studying the global and for engaging in constructive critique.     

Urban development in the southern Great Plains: effects of atmospheric NO<Subscript>x</Subscript> on the long-lived post oak tree (<Emphasis Type="Italic">Quercus stellata</Emphasis>)

Concentrated human activities such as the burning of fossil fuels have resulted in chronic nitrogen (N) additions to urban ecosystems. We predicted that urban development in North Texas (NTX; the largest “megapolitan” region in the Great Plains) would be positively correlated with atmospheric concentrations of nitrogen oxides (NO_x) and with the leaf tissue quality (lower C:N ratio) and herbivory of the long-lived native tree, post oak (Quercus stellata). Data from air monitoring stations were used to calculate distance-weighted estimates of atmospheric NO_x for 11 sites of differing urban development across NTX. Soil samples were collected at each site along with post oak leaves, estimates of herbivory, and measurements of tree size. Percent urban development was strongly positively correlated with atmospheric NO_x concentrations, though there was no correlation between atmospheric NO_x and soil N. There was a positive relationship between soil N and leaf tissue quality, but only where atmospheric NO_x was relatively low, possibly due to factors that covary with urban development. Herbivory was not significantly correlated with leaf tissue quality, but leaves from the two most urban sites had the greatest amount of insect herbivory. The NO_x concentrations in NTX were lower than other industrialized cities, which may be due to climate and topography differences or the relatively young age of this urban area. This study adds to the expanding body of literature examining how urban ecosystems are affected (or not) by N deposition and suggests that interactions among NO_x, soils, and plants are complex and sometimes, counterintuitive.