Demand for contract enforcement in a barter environment

Do greater potential gains from trade enhance or erode contracting institutions? In an anonymous exchange environment traders can sign a contract, hence agreeing to interact with the assigned partner, or wait till the next match. Any contract can be endorsed (for a payment) by the enforcement agency, which then observes the interaction with a positive probability known to the traders and punishes any detected infractors. Demand for contract enforcement is the highest amount a proposer of a contract is ready to pay to the agency, in a stationary subgame perfect equilibrium. It may be strictly positive, as we show, even when contracts are broken. Surprisingly, larger potential gains from exchange may dampen the demand, but not always: the demand is boosted under agencies that oversee the interactions frequently.     

Modelling two way contingency tables with recursive logits and odds ratios

In this work a new type of logits and odds ratios, which includes as special cases the continuation and the reverse-continuation logits and odds ratios, are defined. We prove that these logits and odds ratios define a parameterization of the joint probabilities of a two way contingency table. The problem of testing equality and inequality constraints on these logits and odds ratios is examined with particular regard to two new hypotheses of monotone dependence. Work partially supported by a MIUR2004 grant. Preliminary findings have been presented at SIS (Società Italiana di Statistica) Annual Meeting, Torino, 2006.     

A generalized scheffé method of multiple comparisons

Standard resulrs on the extrema of quotients of quadratic forms are extended to the non-negative definite case. The maximum and the set over which it is achieved are characterized explicitly both in terms of generalized inverse matrices and generalized eigenvalues. These results become the basis of Scheffe type multiple comparisons in the usual way. To demonstrate their application to statistics with singular covariance matrices, the method is detailed for Mantel-Haenszel, Breslow, and Cox statistics. An example is presented illustrating a situation where the proposed Scheffe type comparisons may be better than the pairwise method.     

A new mixture model on the simplex

This paper is meant to introduce a significant extension of the flexible Dirichlet (FD) distribution, which is a quite tractable special mixture model for compositional data, i.e. data representing vectors of proportions of a whole. The FD model displays several theoretical properties which make it suitable for inference, and fairly easy to handle from a computational viewpoint. However, the rigid type of mixture structure implied by the FD makes it unsuitable to describe many compositional datasets. Furthermore, the FD only allows for negative correlations. The new extended model, by considerably relaxing the strict constraints among clusters entailed by the FD, allows for a more general dependence structure (including positive correlations) and greatly expands its applicative potential. At the same time, it retains, to a large extent, its good properties. EM-type estimation procedures can be developed for this more complex model, including ad hoc reliable initialization methods, which permit to keep the computational issues at a rather uncomplicated level. Accurate evaluation of standard error estimates can be provided as well.     

Public Health Institutions,Clinical Research and Protection System of Patients’ Rights: An Impact Evaluation of Public Policy

Public health institutions are involved in human experimentations, which is a specific phase of pharmaceutical industry’s production process. These medical centers collect clinical evidence about experimental treatments and, at the same time, they have to guarantee patients’ safety through appropriate Institutional Review Boards. Taking human experimentation into account, this work aims at estimating a public policy designed to reduce transaction costs that are related to the protection system of patients’ rights, with both a normative and positive approach. On the one hand, considering a sample of European countries as counterfactual, an empirical analysis is performed in order to estimate the impact of a national law aimed at harmonizing the procedure to obtain opinions on clinical trials. On the other hand, an alternative law, which might be able to favor the exchange between pharmaceutical companies and patients, is proposed.     

The effects of pre-IPO corporate activity on newly-public firms' growth

We investigate firms' pre-IPO corporate activity. We find that firms involved in extraordinary – i.e., beyond momentum – amounts of acquisitions, JVs, and alliances in the year leading up to their IPOs (1) are more likely to engage in post-IPO corporate activity; and (2) enter into their first post-IPO transaction twice as fast as other firms. Our results indicate that signaling via extraordinary corporate activity can have a significant effect on entrepreneurial firms’ growth. The implications are discussed.     

Perceptions of grandparents who provide auxiliary care: value transmission and child‐rearing practices

A grounded theory qualitative study was developed to explore how grandparents perceive their role as socializing agents. Forty‐two grandparents with grandchildren aged from 6 to 12 years old participated in this study. Data were collected through focus groups, which were conducted until reaching data saturation and analyzed using the constant comparative method. Four general conclusions emerged from the study: (i) grandparents recognized the importance of getting involved in the socialization of grandchildren as supporters of parents' socializing role, and the need to adapt to social changes; (ii) they emphasized traditional value that were perceived in decline, and combination of warmth and involvement were considered the best way to help grandchildren internalize values; (iii) interaction with grandchildren helped grandparents to feel active and useful, increased their life purpose and gave them a second chance to enjoy what they could not with their own children; and (iv) grandparents also accused burden and role ambiguity. These results show the importance of developing family policies that recognize grandparents' socializing role. Also, interventions that promote strategies that enable grandparents to perform their role more successfully and to cope with possible family conflicts should be developed.     

Friendships in late life: A rural-urban comparison

This study examines the friendship patterns of older adults living in rural and urban areas. The sample consisted of 132 urban adults and 126 rural adults, 65 years of age and older. Respondents were randomly selected and interviewed in their own homes. While both groups were involved in joint social activities and helping behaviors with their friends, there was a distinction in the type of involvement according to geographical location.Karen Roberto is Assistant Professor and Coordinator of the Gerontology Program at the University of Northern Colorado. Her current research interests include women's health issues in aging and older people's involvement with informal support networks. Dr. Roberto holds a Ph.D. in Human Development from Texas Tech University.Jean Pearson Scott is Associate Professor in the Department of Human Development and Family Studies at Texas Tech University. Dr. Scott earned her Ph.D. from the University of North Carolina at Greensboro and is currently conducting research on Alzheimers Disease in the family and the rural elderly.This is a revised version of a paper presented at the Families and Close Relationships: Individuals in Social Interaction Conference, Lubbock, TX, February, 1982.This study was supported by a grant from AARP Andrus Foundation and the Institute for University Research, College of Home Economics, Texas Tech University, Lubbock, Texas 79409.     

BULIMIA: THE TRANSGENERATIONAL VIEW*

Within families presenting with bulimia, there exist interactional patterns that can be said to enable, and perpetuate, the binge-eating and purging symptoms of the identified patient. A transgenerational treatment method is proposed, which not only intervenes in ongoing dysfunctional patterns, but also provides a frame for creating a therapeutic metaphor (“legacy”) to direct the therapy. Rationale and stages of the treatment process are outlined, and a case example is given to illustrate use of the transgenerational frame.