Graphical evaluation of robust parameter designs based on extended scaled prediction variance and extended spherical average prediction variance

For any response surface design, there are locations in the design region where responses are estimated well and locations where estimation is relatively poor. Consequently, graphical evaluation—such as variance dispersion graphs and the fraction of design space—is used as an alternative to a single-valued criterion. Such plots are used to investigate and compare the prediction capabilities of certain response surface designs currently available to the researcher. In this article, we propose the extended scaled prediction variance and extended spherical average prediction variance as prediction methods. We also illustrate how graphical methods can be employed to evaluate robust parameter designs.     

Bridge Estimation for Linear Regression Models with Mixing Properties

Penalized regression methods have for quite some time been a popular choice for addressing challenges in high dimensional data analysis. Despite their popularity, their application to time series data has been limited. This paper concerns bridge penalized methods in a linear regression time series model. We first prove consistency, sparsity and asymptotic normality of bridge estimators under a general mixing model. Next, as a special case of mixing errors, we consider bridge regression with autoregressive and moving average (ARMA) error models and develop a computational algorithm that can simultaneously select important predictors and the orders of ARMA models. Simulated and real data examples demonstrate the effective performance of the proposed algorithm and the improvement over ordinary bridge regression.     

Semiparametric Bayesian hierarchical models for heterogeneous population in nonlinear mixed effect model: application to gastric emptying studies

Gastric emptying studies are frequently used in medical research, both human and animal, when evaluating the effectiveness and determining the unintended side-effects of new and existing medications, diets, and procedures or interventions. It is essential that gastric emptying data be appropriately summarized before making comparisons between study groups of interest and to allow study the comparisons. Since gastric emptying data have a nonlinear emptying curve and are longitudinal data, nonlinear mixed effect (NLME) models can accommodate both the variation among measurements within individuals and the individual-to-individual variation. However, the NLME model requires strong assumptions that are often not satisfied in real applications that involve a relatively small number of subjects, have heterogeneous measurement errors, or have large variation among subjects. Therefore, we propose three semiparametric Bayesian NLMEs constructed with Dirichlet process priors, which automatically cluster sub-populations and estimate heterogeneous measurement errors. To compare three semiparametric models with the parametric model we propose a penalized posterior Bayes factor. We compare the performance of our semiparametric hierarchical Bayesian approaches with that of the parametric Bayesian hierarchical approach. Simulation results suggest that our semiparametric approaches are more robust and flexible. Our gastric emptying studies from equine medicine are used to demonstrate the advantage of our approaches.     

Kernel Density Estimator From Ranked Set Samples

We study kernel density estimator from the ranked set samples (RSS). In the kernel density estimator, the selection of the bandwidth gives strong influence on the resulting estimate. In this article, we consider several different choices of the bandwidth and compare their asymptotic mean integrated square errors (MISE). We also propose a plug-in estimator of the bandwidth to minimize the asymptotic MISE. We numerically compare the MISE of the proposed kernel estimator (having the plug-in bandwidth estimator) to its simple random sampling counterpart. We further propose two estimators for a symmetric distribution, and show that they outperform in MISE all other estimators not considering symmetry. We finally apply the methods in this article to analyzing the tree height data from Platt et al. (1988 Platt, W.J., Evans, G.M., Rathbun, S.L. (1988). The population dynamics of long-lived conifer (Pinus plaustris) (1988). Amer. Natrualist 131:491–525.[Crossref], [Web of Science ®] , [Google Scholar]) and Chen et al. (2003 Chen, Z., Bai, Z., Sinha, B.K. (2003). Ranked Set Sampling: Theory and Applications. New York: Springer. [Google Scholar]).     

Differences in soil chemical properties with distance to roads and age of development in urban areas

The main objective of this study was to characterize variation in soil chemical properties with length of urbanization period and distance to roads. Urban boundaries from 1920’s (old), 1960’s (middle) and 2000’s (new) were identified for three cities in northeast Ohio: Massillon, Wooster and Canton. Within each identified historic boundary, soil samples were collected from two road-side and two interior lawns in one public school site in each city. Thus, there were three urban age and two distance-to-roads classes. Soil particle composition and basic chemical properties including pH, available phosphorus (P), exchangeable potassium (K), calcium (Ca), magnesium (Mg), cation exchange capacity (CEC), nitrate, total carbon (C), total nitrogen (N), and soil organic matter (SOM) were measured. Two notable spatio-temporal patterns appeared repeatedly in the data set. First, total C, total N and SOM were higher in the soils of old (>50 years) urban sites than of newly developed sites. Similar, but not always significant, trends in soil pH, and exchangeable Ca were also observed. Second, road-side soils had higher pH, Ca, total C and N than interior sites regardless of urban age. These data indicate that key soil chemical properties can vary in predictable ways with urban age and distance-to-roads classes. Such variations in key soil chemical properties may influence or reflect soil biota and biogeochemical processes in urban soils.     

Financial Risk Attitude and Behavior: Do Planners Help Increase Consistency?

This study is the first to evaluate the effect of sources of information on households’ consistency between their risk attitude when making savings and investment decisions and risk behavior displayed when they do save and invest. As the responsibility is being shifted to individuals to save for their own financial future, it is important that individuals and households save and invest in a manner that is consistent with their financial risk tolerance. Financial planners were found to provide significant value to households on the consistency of their financial risk attitude and behavior. The implications of this work are far-reaching in the financial planning arena.     

Effects of crisis efficacy on intentions to follow directives during crisis

Self-efficacy has consistently been a useful predictor of behavioral intentions as a construct in many theories; yet, its role in audience adherence to instructing information during crisis is relatively unexplored. A national survey (N = 454) examines self-efficacy in public response to crisis directives and develops the concept of crisis efficacy as an important area for future research. In three crisis contexts (food-borne illness, weather emergency, and public health disease threat), crisis efficacy, along with several demographics, significantly predicted public response to instructing information. Crisis efficacy emerges as a construct with great potential to inform message design in crisis communication.     

Global poverty estimates based on 2011 purchasing power parity: where should the new poverty line be drawn?

This paper aims to present a new global poverty line based on the 2011 Purchasing Power Parity (PPP). To calculate a new global poverty threshold based on 2011 PPP, this paper moves away from the World Bank’s method of anchoring a single global poverty line on the national poverty lines of the 15 poorest countries. It instead proposes an alternative method of using equivalent poverty lines. Each country is shown to have a different equivalent poverty line. This paper finds that there is no single international poverty line in 2011 PPP that is equivalent to $1.25 in 2005 PPP. Single poverty lines vary for each region because countries have experienced different inflation rates and have different PPP conversion rates between 2005 and 2011. To calculate a single poverty line in 2011 PPP, this paper measures the weighted average of equivalent poverty lines of 101 countries around the globe with weights proportional to their populations. Based on the new method, the corresponding poverty line is estimated at $1.93 in 2011 PPP. The World Bank has officially adopted the poverty line of $1.90 in 2011 PPP. This paper demonstrates that our proposed poverty line performs better than the World Bank’s in terms of preserving the real purchasing power of the previous line of $1.25 in 2005 PPP. Given the new poverty threshold of $1.93, the number of poor worldwide is reduced by 6.42 million, with the reduction largely occurring in South Asia and Sub-Saharan Africa.     

Bridging the territorial divide: immigrants’ cross-border communication and the spatial dynamics of their kin networks

The transnational perspective emphasises the persistence of immigrants’ home country connections, yet existing research adds little to our understanding of the mechanisms by which cross-border ties are maintained. We use nationally representative data of immigrants in Spain to describe changes in their kin network and study how two characteristics, migration stage (whether kin already resided in Spain at the time of emigration and whether any kin remained in the birth country (BC) at the time of interview) and relationship-specific locations of kin (children, parents, spouse, siblings), influence the frequency of cross-border communication. We find an expansion in the total number of kin largely due to childbearing and marriage. The average fraction of migrants’ immediate kin in Spain shifts from 6% to 41%. The presence of at least one kin in the BC increases the frequency of cross-border communication, but with the exception of siblings, the presence of family already in Spain at the time of emigration does not. Siblings and parents were far more likely to retain a BC presence, but they were less likely than spouses or children to be contacted daily. While these ties are generally long-lasting, communication wanes as immigrant embeddedness in the receiving country grows.     

Trajectories of Community-Based Service Use: The Importance of Poverty and Living Arrangements

ABSTRACT

This study examined how older adults’ living arrangements and poverty status affected their use of in-home health, functional, and out-of-home services over time. Using eight waves of data from the Korea Welfare Panel Study, we employed a logistic mixed-effect model to analyze how poverty and living arrangements affect community-based service use. Living-alone older adults and elder-only couples were more likely than co-residing households to use services. Elder-only couples, when poor, were more likely to use in-home and out-of-home services over time. Understanding predictors of community-based service use over time enables researchers and policymakers to better understand the process of aging-in-place.