Testing for and against a set of linear inequality constraints in a multinomial setting

There are numerous situations in categorical data analysis where one wishes to test hypotheses involving a set of linear inequality constraints placed upon the cell probabilities. For example, it may be of interest to test for symmetry in k × k contingency tables against one-sided alternatives. In this case, the null hypothesis imposes a set of linear equalities on the cell probabilities (namely p_ij = P_ji ×i > j), whereas the alternative specifies directional inequalities. Another important application (Robertson, Wright, and Dykstra 1988) is testing for or against stochastic ordering between the marginals of a k × k contingency table when the variables are ordinal and independence holds. Here we extend existing likelihood-ratio results to cover more general situations. To be specific, we consider testing H_t,0 against H₁ - H₀ and H₁ against H₂ - H ₁ when H₀:k × i=1 p_ix_ji = 0, j = 1,…, s, H₁:k × i=1 p_ix_ji × 0, j = 1,…, s, and does not impose any restrictions on p. The x_ji's are known constants, and s × k - 1. We show that the asymptotic distributions of the likelihood-ratio tests are of chi-bar-square type, and provide expressions for the weighting values.     

Some issues related to the topological aggregation of preferences

This paper deals with the topological approach to social choice theory initiated by Chichilnisky. We study several issues concerning the existence and uniqueness of Chichilnisky rules defined on preference spaces. We show that on topological vector spaces the only additive, anonymous, and unanimous aggregation n-rule is the convex mean. We study the case of infinite agents and show that an infinite Chichilnisky rule might be considered as the limit of rules for finitely many agents. Finally, we show that under some restrictions on the preference space, the existence of a Chichilnisky rule for every finite case implies the existence of a weak Chichilnisky rule for the infinite case.     

Community and individual acceptance: family planning services in the Sudan

The Sudan Community-Based Health Project, initiated by the University of Khartoum in cooperation with the Ministry of Health in 1980, sought to test the proposition that government-trained village midwives could provide maternal-child health and birth spacing services in addition to their ongoing obstetrical duties. The project area encompassed 92,000 people in 93 villages. The 120 midwives serving the project area received training in 4 interventions -- oral rehydration therapy, maternal and child nutrition, immunization, and birth spacing -- and introduced these services by means of 3 rounds of household visits over a 5-month period. Comparison of pre- and post-intervention survey data indicates that village midwives can indeed be used successfully to promote not only contraceptive use, but also health attitudes and practices that are positively associated with fertility regulation. Between the 2 surveys, the percentage of women who ever used contraception increased from 22% to 28%, while the percentage of current users rose from 10% to 13%. Parity was significantly related to current use; each child born multiplied the likelihood of contraceptive acceptance (by a factor of 0.76 in the post-intervention sample). Maternal education was the socioeconomic variable that most enhanced receptivity to contraceptive acceptance after the project's interventions. In terms of community-level variables, village location along the Nile and proximity to a paved road were significant correlates of contraceptive use. When variables related to the project itself were analyzed, women with vaccinated children were found to be twice as likely to contracept as those with nonvaccinated children and women who believed breast feeding should be continued during diarrhea episodes were 1.5 times more likely to use birth spacing than those who did not. Although midwives did not specifically emphasize contraceptive use, it appears women who were encouraged by midwives to take positive steps in the area of child health were also likely to become more innovative in terms of fertility regulation.     

Permissions and the social context

By focusing on formal intensive interview research, this essay explores how the sociohistorical context influences the routine procedures by which sociologists obtained permission to conduct their studies. We examine the permissions process within the specific historical context of the 1950s and contrast it with contemporary issues of informed consent. The need for a more theoretical and situational understanding of permissions is identified, both in regard to human—subjects regulations and social control. Her most recent books areMadwives: Schizophrenic Women in the 1950s (Rutgers University Press, 1987) andGender Issues in Field Research (Sage, 1988). She has written extensively in the fields of mental illness and social control. Her current research focuses on the sociological analysis of art and culture as well as the processes of doing and writing fieldwork. She is also the co-managing editor of theMid-American Review of Sociology.     

How leader humility helps teams to be humbler,psychologically stronger,and more effective: A moderated mediation model

We hypothesize that (a) the level of humility expressed by leaders predicts team performance through, serially, team humility and team PsyCap, and (b) the strength (i.e., consensus within the team) of the leader humility, team humility and team PsyCap moderates the paths of that hypothesized model. A sample comprising 82 teams (82 leaders; 332 team members) was collected. Team members reported leader humility, team humility and team PsyCap. Leaders reported team performance. To handle the risks of common method bias, each mediating path of the hypothesized model is based on data from two different subsamples within each team. Our model's most novel theoretical contribution is the (moderated mediated) connection between leader humility, collective humility, and team PsyCap, and this was consistently supported in our data. Our inconsistent findings dealing with the relationship between team PsyCap and performance is well established in the literature and our results in both sub-samples were in the theorized direction. The study contributes to understand why, how and when humble leaders are more effective.     

A parallel multi-population genetic algorithm for a constrained two-dimensional orthogonal packing problem

This paper addresses a constrained two-dimensional (2D), non-guillotine restricted, packing problem, where a fixed set of small rectangles has to be placed into a larger stock rectangle so as to maximize the value of the rectangles packed. The algorithm we propose hybridizes a novel placement procedure with a genetic algorithm based on random keys. We propose also a new fitness function to drive the optimization. The approach is tested on a set of instances taken from the literature and compared with other approaches. The experimental results validate the quality of the solutions and the effectiveness of the proposed algorithm.     

Challenges in Development and Implementation of Health‐Risk‐Based Soil Quality Guidelines: Turkey's Experience

Management of contaminated sites is a critical environmental issue around the world due to the human health risk involved for many sites and scarcity of funding. Moreover, clean‐up costs of all contaminated sites to their background levels with existing engineering technologies may be financially infeasible and demand extended periods of operation time. Given these constraints, to achieve optimal utilization of available funds and prioritization of contaminated sites that need immediate attention, health‐risk‐based soil quality guidelines should be preferred over the traditional soil quality standards. For these reasons, traditional soil quality standards are being replaced by health‐risk‐based ones in many countries and in Turkey as well. The need for health‐risk‐based guidelines is clear, but developing these guidelines and implementation of them in contaminated site management is not a straightforward process. The goal of this study is to highlight the problems that are encountered at various stages of the development process of risk‐based soil quality guidelines for Turkey and how they are dealt with. Utilization of different definitions and methodologies at different countries, existence of inconsistent risk assessment tools, difficulties in accessing relevant documents and reports, and lack of specific data required for Turkey are among these problems. We believe that Turkey's experience may help other countries that are planning to develop health‐risk‐based guidelines achieve their goals in a more efficient manner.     

Predictors of Adolescent Participation in Organized Activities: A Five‐Year Longitudinal Study

This study examined (a) growth curves of youth participation in sports, performance and fine arts, and youth clubs throughout the high school years and (b) the associations between a series of predictors and the initial participation rates and growth over time. The predictors included individual, friend, and family factors. The moderating effect of youths' gender was also examined. Study participants were 272 youths (55% girls, M_age=12.4 years) and their parents. The predictors were assessed in Grade 6 and were based on reports by youths, parents, teachers, and classmates. Participation in organized activities was assessed annually from Grades 7 to 10. Altogether, the findings revealed that participation in sports, performance and fine arts, and youth clubs remains stable across the high school years. However, interindividual differences were found in the participation growth curves. This variation was predicted by individual, friend, and family factors, mostly with respect to sports activities.