Adjusting Cornish–Fisher expansions and confidence intervals for the effect of roundoff

Suppose we want to estimate some smooth function of two types of parameters. The first can be estimated by sample means, while the second is known exactly up to the number of decimal places recorded, that is they are subject to roundoff. We obtain the Cornish–Fisher expansions and associated nonparametric confidence intervals for such functions. These results are illustrated by a simulation study.     

Expressions for the distribution and percentiles of the sums and products of chi-squares

Linear combinations of central or non-central chi-squares occur naturally in a variety of contexts. The products of chi-squares occur when a variance has a chi-square prior and in electrical engineering. Here, we give expansions for their distribution and quantiles and also for the products of the powers of chi-squares, including ratios. These provide much more accurate approximations than those based on asymptotic normality. The larger the degrees of freedom or the larger the non-centrality parameters, the better the approximations. We give the first four terms of these expansions. These provide approximations with errors smaller by five magnitudes than those based on asymptotic normality or on Satterthwaite's approximation. His method matched the first two moments of the target and a multiple of a chi-square and is only a first-order approximation like that based on the central limit theorem. We show that it can be made second order by matching the first three moments. The appendices show how to obtain analytical expressions for the distribution of weighted sums of chi-squares.     

Procedures for investigating outliers when estimating in the general univariate linear situation-nonfull rank case

This paper is a continuation of GGD = Golub, Guttman and Dutter (1973) and DG = Dutter and Guttman (1974a), and will deal with the problem of how to handle outliers in the general univariate linear model situation y = Xθ + ?, ? = N(0, σ²I).when X is not of full rank, and where interest is in the estimation of τ = Bθ, where τ is assumed to be estimable. The special case B = X, that is, interest is in η = Xθ, is discussed.     

Multidimensional Poverty: Measurement,Estimation, and Inference

Calibration in macroeconomics involves choosing fre parameters by matching certain moments of simulted models with those of data. We formally examine this method by treating the process of calibration as an econometric estimator. A numerical version of the Mehra-Prescott (1985) economy is the setting for an evaluation of calibration estimators via Monte Carlo methods. While these estimators sometimes have reasonable finite-sample properties they are not robust to mistakes in setting non-free parameters. In contrast, generalized method-of-moments (GMM) estimators have satisfactory finite-sample characteristics, quick convergence, and informational requirements less stringent than those of calibration estimators. In dynamic equilibrium models in which GMM is infeasible we offer some suggestions for improving estimates based on calibration methodology.     

Punctuated Entropy as Culture-Induced Change:The Case of the Exxon Valdez Oil Spill

This article grew out of the obser-vation that as disaster events increase in frequency and severity , recovery from certain kinds , or com-binations of , disasters becomes increasingly diffi-cult, i...     

Derrick Bell,CRT, and educational leadership 1995–present

Critical Race Theory (CRT) has become a centered conceptual framework to understand American education and reform (Ladson-Billings and Tate 1995; Solorzano and Yosso; 2001; Decuir and Dixon 2004). Indeed, educational leadership scholars have not been far behind in recognizing the explicative and powerful role of CRT studies in their work (Lopez 2003; Parker and Villalpando 2007). As we acknowledge the role of CRT, we cannot do so without reflecting on the life and works of the quintessential Critical Legal Studies (CLS) scholar Derrick Bell (1930–2011). In this article, we use Bell’s collective works to analyze current trends and research in educational leadership. We bring his works into conversation not only with conceptions of instructional and distributed leadership, but with the palpability that CRT has on the current state of educational reform. More specifically, we use Bell’s theories of interest convergence and conversations around ‘racial remedies’ to understand two recent trends in educational leadership: discourses of social justice leadership and the move toward data-driven leadership behaviors. We ask questions like: what has been the impact of research discourses social justice on the education of African American and Latino urban youth? And, how has the current social structures benefited from such discourses? We conclude with recommendations for educational leadership researchers and professors, and encourage them to consider race as an integral part of their works.     

Supply Chain Knowledge and Performance: A Meta‐Analysis

Many firms make significant investments into developing and managing knowledge within their supply chains. Such investments are often prudent because studies indicate that supply chain knowledge (SCK) has a positive influence on performance. Key questions still surround the SCK–performance relationship, however. First, what is the overall relationship between SCK and performance? Second, under what conditions is the relationship stronger or weaker? To address these questions, we applied meta‐analysis to 35 studies of the SCK–performance relationship that collectively include more than 8,400 firms. Our conservative estimate is that the effect size of the overall relationship is  = .39. We also find that the SCK–performance relationship is stronger when (i) examining operational performance, (ii) gathering data from more than one supply chain node, (iii) gathering data from multiple countries, (iv) examining service industries, and (v) among more recently published studies. We also found that studies that embraced a single theory base (as opposed to using multiple ones) had a stronger SCK–performance relationship. Looking to the future, our meta‐analysis highlights the need for studies to (i) include lags between the measurement of SCK and performance, (ii) gather upstream data when examining innovation, (iii) examine SCK within emerging countries, and (iv) provide much more information relative to the nuances of the SCK examined.     

Rational choices: an ecological approach

Theory and Decision - We address the oft-repeated criticism that the demands which the rational choice approach makes on the knowledge and cognition of a decision-maker (DM) are way beyond the...     

Activity of free-roaming domestic cats in an urban reserve and public perception of pet-related threats to wildlife in New Zealand

Urban Ecosystems - Across the globe there is an increasing number of initiatives promoting biodiversity in urban areas – both for the benefit of native wildlife and the people who live in...     

What do urban college students really think about health insurance? A qualitative study

Abstract

Objective: To determine barriers and opportunities to health insurance enrollment among an undergraduate students at a large urban university. Participants: Participants were 31 college students enrolled in 4-year and community colleges in the City University of New York (CUNY), and six health services and insurance enrollment specialists who facilitate and assist in the health insurance enrollment process for CUNY students. Methods: Focus groups were conducted with students and in-depth interviews with key informants in May 2017. Results: The research revealed important insights into how students perceive and value insurance and yielded recommendations for the university to improve enrollment of its students. Conclusions: Many colleges can increase student enrollment in health insurance by informing and educating students about the process. Improving enrollment processes can increase insurance rates and improve student population health.