An algorithmic approach to construct D-optimal saturated designs for logistic model

In this paper, locally D-optimal saturated designs for a logistic model with one and two continuous input variables have been constructed by modifying the famous Fedorov exchange algorithm. A saturated design not only ensures the minimum number of runs in the design but also simplifies the row exchange computation. The basic idea is to exchange a design point with a point from the design space. The algorithm performs the best row exchange between design points and points form a candidate set representing the design space. Naturally, the resultant designs depend on the candidate set. For gain in precision, intuitively a candidate set with a larger number of points and the low discrepancy is desirable, but it increases the computational cost. Apart from the modification in row exchange computation, we propose implementing the algorithm in two stages. Initially, construct a design with a candidate set of affordable size and then later generate a new candidate set around the points of design searched in the former stage. In order to validate the optimality of constructed designs, we have used the general equivalence theorem. Algorithms for the construction of optimal designs have been implemented by developing suitable codes in R.     

Measuring to Improve Versus Measuring to Prove: Understanding the Adoption of Social Performance Measurement Practices in Nascent Social Enterprises

Social enterprises are described as organizations with dual objectives—social and commercial. While the measurement of commercial performance is relatively straightforward and well understood, our understanding of the factors related to measuring social performance is more ambiguous. Is the adoption of social performance measurement (SPM) practices more related to external pressures, such as the need to demonstrate legitimacy to funders and peers, or is it more closely related to the growing rationalization within the social sector? We examine the relationship between external and internal factors and the adoption of SPM using a novel dataset of 1864 nascent social enterprises from around the world. Our findings suggest support for the argument that the adoption of SPM in social enterprise is related to the growing rationalization of the social sector, which challenges some of the past research on this topic, and provides a more nuanced perspective of SPM in social enterprise.     

Can Institutional Support Improve Volunteer Quality? An Analysis of Online Volunteer Mentors

VOLUNTAS: International Journal of Voluntary and Nonprofit Organizations - Volunteer management practices have been shown to have positive effects on employees in terms of skill development, job...     

An Empirical,Nonparametric Simulator for Multivariate Random Variables with Differing Marginal Densities and Nonlinear Dependence with Hydroclimatic Applications

Multivariate simulations of a set of random variables are often needed for risk analysis. Given a historical data set, the goal is to develop simulations that reproduce the dependence structure in that data set so that the risk of potentially correlated factors can be evaluated. A nonparametric, copula‐based simulation approach is developed and exemplified. It can be applied to multiple variables or to spatial fields with arbitrary dependence structures and marginal densities. The nonparametric simulator uses logspline density estimation in the univariate setting, together with a sampling strategy to reproduce dependence across variables or spatial instances, through a nonparametric numerical approximation of the underlying copula function. The multivariate data vectors are assumed to be independent and identically distributed. A synthetic example is provided to illustrate the method, followed by an application to the risk of livestock losses in Mongolia.     

From Legitimacy to Learning: How Impact Measurement Perceptions and Practices Evolve in Social Enterprise–Social Finance Organization Relationships

VOLUNTAS: International Journal of Voluntary and Nonprofit Organizations - While the links between the fields of social enterprise and social finance appear apparent, academic research on the...     

A study of low birth weight infants in an urban community

The study concerns the problem of low birth weight as seen in a prospectively studied cohort from a South Delhi urban community covering 23,700 families and 1,19,799 population over a four year period from 1969-73. The incidence of low birth weight was 22.9 per cent of which 2.7 per cent had a birth weight of 2000 gms. or less and 20.2 per cent had a birth weight 2001-2500 gms. Maternal height of 140 cms or less and pregravid weight of 35 kg or less were associated with the occurrence of low birth weight infant. The mortality was related inversely to birth weight and the gestation affected the outcome directly. The mortality rates declined sharply in infants of birth weight 2001-2500 gms but was still high as compared to infants of birth weight more than 2.5 kg. The later physical growth was affected by the initial birth weight. The study was conducted under the research project 01-658-2 funded by the National Centre for Health Statistics, 3700 East West Highway, Hyattsville, Maryland-20782, U.S.A.     

Optimal Crop Choice,Irrigation Allocation,and the Impact of Contract Farming

The changing climate and concerns over food security are prompting a new look at the supply chain reliability of products derived from agriculture, and the potential role of contract farming as a mechanism to address climate and price risk while contributing toward crop diversification and water use efficiency is also emerging. In this study, the decision problem of a farmer associated with allocating his land among different crops with varying water requirements is considered, given that a subset of the crops may be associated with a forward contract that is being offered by a buyer. The problem includes a decision to acquire a certain amount of irrigation water capacity prior to the season and to allocate this capacity as irrigation water to be applied during the season to each of the crops selected. Rainfall in the growing season and the market price of each crop at the end of the season are considered to be random variables. Two stochastic programming models are developed to consider facets of this problem and to understand how contracts that reduce market price uncertainty from the problem may change the farmer's decision. The structural properties of these models are discussed, and selected implications are illustrated through an application to data from the Ganganagar district in Rajasthan, India.     

Migration and livelihood constellations: Assessing common themes in the face of environmental change in Somalia and among Agro-Pastoral peoples

Research on migration has become more challenging due to at least four factors: (1) more complex migration traditions; (2) the development of migration economies that engage many types of migrants from ever more social and cultural backgrounds; (3) increasing likelihood of climate change-driven environmental migration; and (4) increasing likelihood of conflict-based migration in some contexts. These developments have shaken economic theories of migration and have encouraged interdisciplinary, methodologically mixed, qualitative and quantitative research and analysis. From a review of the literature, we have gleaned 11 common themes about environmental, economic and conflict migration that we differentiate by process (migration behaviours that are still evolving) and patterns (migration behaviours that have become customary). We then consider how positive and negative dimensions of migration can be captured and represented with close attention to livelihood constellations (multiple economic activities combined by individuals, households and families). Finally, focusing on Somalia and agro-pastoral peoples generally, where recent environmental and conflict migration have been added to decades of economic migration and centuries of seasonal, environmental migration associated with pastoralism, we combine historical and qualitative work to demonstrate the value of a livelihood constellation perspective.     

VOLUNTAS Virtual Issue: Social Enterprise

VOLUNTAS: International Journal of Voluntary and Nonprofit Organizations -