Approximation Multivariate Distribution with Pair Copula Using the Orthonormal Polynomial and Legendre Multiwavelets Basis Functions

We concentrate on constructing higher dimensional distributions using a fast growing graphical model called Vine/ pair-copula model which has been introduced and developed by Joe, Cooke, Bedford, Kurowica, Daneshkhah, and others. They first construct a n-dimensional copula density by stacking together n(n ? 1)/2 bivariate copula density, and they then approximate arbitrarily well these bivariate copulas and the corresponding multivariate distribution using a semi-parametric method. One constructive approach involves the use of minimum information copulas that can be specified to any required degree of precision based on the available data (or possibly based on the experts’ judgments). By using this method, one is able to use a fixed finite dimensional family of copulas to be employed in terms of a vine construction, with the promise of a uniform level of approximation.

The basic idea behind this method is to use a two-dimensional ordinary polynomial series to approximate any log-density of a bivariate copula function by truncating the series at an appropriate point. We make this approximation method more accurate and computationally faster by using the orthonormal polynomial and Legendre multiwavelets (LMW) series as the basis functions. We show the derived approximations are more precise and computationally faster with better properties than the one proposed previous method in the literature. We then apply our method to modeling a dataset of Norwegian financial data that was previously analyzed in the series of articles, and finally compare our results by them. At the end, we present a method to simulate from the approximated models, and validate our approximation using the simulation results to recover the same dependency structure of the original data.     

Social context and personal expenditures for health care: federal policy and the experience of older adults in the 1970s

The relationship between the intent and the outcome of legislated social policy is discussed. Specifically, this study documents some effects of federal health reimbursement and income policy in the late 1960s and early 1970s on health care behavior and expenditures in the decade 1970-1980. The Longitudinal Retirement History Study (LRHS), containing information on a panel of 6,270 men and unmarried women aged 58 to 63 in 1969, was used to provide information on the personal health expenditures in this decade. Medicare and Medicaid and the indexing of Social Security became operational at the beginning of the study, which permitted the exploration of intended and observed effects of legislation designed to make health care more accessible and affordable for older adults. As policy intended, utilization increased over the decade as indicated by both increases in the number of panelists with health care bills and increases in the size of total bills (constant dollars). Consistent with federal policy to reduce personal costs, out-of-pocket expenditures and the proportion of total bills paid out of pocket decreased. However, the effects of these federal policy initiatives were constrained by reimbursement rules and the social location of users. For instance, even at the end of the 1970s, out-of-pocket health care expenditures across subpopulations persisted. The 1980s and early 1990s have brought increased concern over the cost of health care and renewed concern over access. Data suggest that future proposals aimed at providing universal coverage along with high out-of-pocket costs may not result in equitable programs, and are likely to have a limited impact on constraining health care costs. The LRHS data indicate that utilization increased despite continued high out-of-pocket costs for all except the lower-income groups, who may be limited in their ability to purchase increasingly costly care.     

Seasonal variation in basic demographic phenomena (the example of Latvian SSR)

The existence of seasonal variation in demographic phenomena in the USSR is illustrated using data for Latvia. The authors provide evidence of seasonal variations in births, marriages, and infant mortality over the period 1970-1986. Changes in the pattern of seasonal variation over time are also noted.     

Repatriation: its role in resolving Africa's refugee dilemma

The literature on Africa's refugees has grown dramatically over the past decade. 2 issues, however, remain relatively unresearched and poorly understood - the plight of urban refugees and the problems associated with repatriation. This article examines the dimensions of the latter. After placing repatriation into the context of contemporary durable solutions applied to the African refugee dilemma, the article examines some of the problems, concerns and frustrations associated with African repatriation exercises in terms of cultural, economic, and political obstacles encountered in the process of repatriation and the concomitant rehabilitation of refugees in their areas of origin. The article is illustrated with examples drawn from the Southern Sudanese repatriation of the early 1970s.     

Determinants involved in the perception of the Necker cube: an application of catastrophe theory

The study is concerned with evaluating interactions at the organic level within the visual perception subsystem of living systems. The reported work focuses on the identification of some of the determinants of multistable perception by experimentally testing a nonlinear dynamical systems (catastrophe) model of the Necker Cube. This technique serves as an advantage over linear threshold models which cannot effectively study multivalued functional relationships. It was proposed that manipulation of two independent control parameters (bias or changing shape by continuously varying perspective lines and selective stimulus shading) was compatible with the subjective dichotomy of bistable perception of the Necker cube. One hundred and twenty naive subjects, categorized by age, sex, and optical aids, were presented with a computer-generated sequence of 63 stimuli (7 shading levels X 9 perspective levels) to which they had to respond as to whether they saw a "hollow" or "solid" image. The work revealed that bias and shading exerted their effects in opposition and that each influenced the other. Both were decisive factors involved in the perception of the cube. These findings are supported by topological and psychological evidence.     

Going home: migration careers of southern Nigerians

Using data on the career migration histories of 533 residents (over 60 years old) of 3 southern Nigerian cities and 471 residents (over 60 years old) of 21 villages within 30 km of these cities, this study compares nonmigrants, returnees, and immigrants on educational and occupational background and ages at 1st and last migration. Findings show that 1) a large majority intend to return home, but many never do; 2) the majority of returnees go home before retirement; 3) migrants over age 65, and especially over age 75, are unlikely to return home; 4) as education and opportunities expand, it is likely that the majority of present cohorts of migrants will spend most of their working lives away from home; 5) economic success may be used to build a house in the city to which one has migrated or to retire in one's home village; 6) most Nigerians look forward to self-employment which facilitates migration and a return home; 7) more widespread wage-employment, with compulsory retirement at age 60, may greatly change the age pattern of returns; and 8) automatic village care is declining as a large proportion of villagers spend their mature years away and those who remain behind may be unable to cope with the increasing number of old people, returnees, and nonmigrants; thus, movement to towns in old age is increasing, especially among women.     

Impacts of Return Migration on Rural U.S. Communities

Rural population loss is caused as much by low in‐migration as by high out‐migration, and for geographically disadvantaged nonmetropolitan counties in the United States, return migration plays a crucial role. This research captures impacts of return migrants on population, economy, and society in declining rural U.S. communities using a qualitative, multisited approach. Interviews conducted at high school reunions with rural returnees in their late 20s to late 40s show that the vast majority of returnees brought spouses and children back with them, increasing the short‐term and long‐term population. They also brought back much needed human capital, including education, job skills, and life experiences, and filled professional positions that are often hard to fill in rural communities. Entrepreneurial activities and self‐employment of many return migrants favorably affected rural economies by improving the employment base and expanding available services. Interviews show how decisions to move back were grounded in social relations that promoted civic engagement. While they mainly moved back for their children and their families, return migrants valued involvement in familiar social networks and the opportunities to make a difference in their rural hometowns.     

Rethinking integration in mixed methods research using data from different eras: lessons from a project about teenage vocational behaviour

Mixed methods research requires integration of qualitative and quantitative data. However, there is debate about how to define integration and what is required for integration to occur. This paper describes a mixed methods research project which revisits datasets from different eras, which were originally instigated for different purposes and had different theoretical frameworks. Using selected results about the relationship between teenagers’ vocational aspirations and adult occupations we show how the research topic and question integrated the projects within a constructivist theoretical position. We argue that reanalysing and comparing historical datasets can provide new insights into a topic even with minimal integration of the data. We recommend a broad definition of integration and reflexive research practice to encourage innovation and diversity in mixed methods research, particularly with regard to reanalysis of datasets from different eras.     

Development of a canonical correlation model involving non linearity and asymmetric variables

The classical canonical correlation analysis (CCA) can characterize, but is limited to, symmetric and linear associations. This study formulated a new model which generalized CCA to non linear associations and asymmetric distributions. Special cases of the proposed model were discussed. The behavior of canonical solutions under varying mixtures of skewness and non linearity (NL) was also examined in a simulation study. In addition, these solutions were compared with some commonly used methods of Hotelling, Spearman, and Kendall. Our empirical findings showed, among others, that for a fixed level of NL, the canonical correlation (ρ) increases as skewness increases. By and large, whether by ρ, likelihood, Akaike information criterion and Bayesian information criterion, the proposed method performed better than the other methods in all degrees of skewness and NL considered. This was further confirmed with real-life data application as Hotelling, Spearman, and Kendall overestimated ρ by 2.08%, 37.81%, and 22.15%, respectively, compared to the proposed technique.     

Volunteering Hierarchies in the Global South: Remuneration and Livelihoods

VOLUNTAS: International Journal of Voluntary and Nonprofit Organizations - This paper explores volunteering and inequality in the global South through an analysis of volunteering remuneration. We...