Stochastic Learning Dynamics and Speed of Convergence in Population Games

We study how long it takes for large populations of interacting agents to come close to Nash equilibrium when they adapt their behavior using a stochastic better reply dynamic. Prior work considers this question mainly for 2 × 2 games and potential games; here we characterize convergence times for general weakly acyclic games, including coordination games, dominance solvable games, games with strategic complementarities, potential games, and many others with applications in economics, biology, and distributed control. If players' better replies are governed by idiosyncratic shocks, the convergence time can grow exponentially in the population size; moreover, this is true even in games with very simple payoff structures. However, if their responses are sufficiently correlated due to aggregate shocks, the convergence time is greatly accelerated; in fact, it is bounded for all sufficiently large populations. We provide explicit bounds on the speed of convergence as a function of key structural parameters including the number of strategies, the length of the better reply paths, the extent to which players can influence the payoffs of others, and the desired degree of approximation to Nash equilibrium.     

DISCONTINUITY OF OUTPUT CONVERGENCE WITHIN THE UNITED STATES: WHY HAS THE COURSE CHANGED?

Has the progress of output convergence changed within the United States? This article examines the output convergence among U.S. states for the last five decades by making several improvements over the extant literature. By applying a battery of convergence tests designed to capture nonlinear transitional dynamics to real output per worker data (i.e., nominal values deflated by state‐level price), we find that output convergence has not been a feature of the continental United States since the 1970s. Instead, output convergence has proceeded among four subgroups within which constituent states have certain characteristics in common. Our regression analysis suggests that state‐level characteristics related to technology and human capital play a crucial role in accounting for the formation and composition of convergence clubs, in agreement with the recent theoretical models of growth and development (e.g., Aghion et al. 2009; Gennaioli et al. 2013b). The level of technology, proxied by patents, turns out to be a consistently significant determinant even after controlling for endogeneity, suggesting that frictions in the diffusion of technology and human capital may have led to clustering of states with different levels of productivity. Our results therefore cast doubt on the common view that diffusion of knowledge and technology across state borders is frictionless. (JEL O47, O51)     

Adapting Zara’s ‘Pronto Moda’ to a value brand retailer

The clothing sector is currently characterised by frequent assortment rotation in stores, a quick response product development and a focus on minimising end-of-campaign stock levels. This paper is based on a case study carried out at a value brand retailer, with a purpose to show how the company increased competitiveness in a market requiring more responsiveness. The case presented shows that the establishment of an adequate supply strategy for differentiated product segments, the introduction of mini-collections, the redesign of business processes (especially the new product development and the order fulfilment processes) and the redesign of the supply chain, lead to a sales increase and purchasing savings. Moreover, the study treats how a value brand retailer, facing different supply chain challenges compared with the leading brands, balance global and local production, lean and agile manufacturing and how it is possible to abandon the traditional two-campaign paradigm in favour of more rapid replenishment.     

Evaluating the Senior Companion Program: a mixed-method approach

This article reports on a mixed-method assessment of the Senior Companion Program (SCP), a federal program which provides volunteer opportunities with small stipends to low-income older adults, 60 years of age and older, who provide companionship and offer assistance to frail community elders. Through four standardized scales and open-ended questions regarding the impact of the SCP in their lives, 34 Senior Companion volunteers and 32 of their clients were interviewed. Informants reported relatively large social networks and low levels of depression and loneliness. Thematic analysis of the qualitative data revealed the benefits of the program for both volunteers and their clients. Themes emerging from the rich narratives included: companionship, independence, reduced anxiety, giving, and rewards. The article concludes with a suggested brief evaluation instrument that directors of SCP programs, and other similar programs, can use to collect data on the impact of their program--something that is required, but often difficult to do.     

Preliminary experiences of the states in implementing the National Family Caregiver Support Program: a 50-state study

Despite increased attention to policy choices to support family and informal caregivers, relatively little is known about states' experiences in providing caregiver support services. This article reports on the first nationwide survey of all 50 states and the District of Columbia in providing caregiver services since the passage of the National Family Caregiver Support Program. State program administrators reported that their program differs from other home and community-based services because of the explicit focus on the family or informal caregiver. Results suggest that despite an increasing availability of caregiver supports in all 50 states, there is also a great unevenness in services and service options for family caregivers across the states and within states.     

Inflammatory effects and immune system correlates of rape

The purpose of this study was to evaluate the feasibility of measuring stress hormones and immunity following rape. The long-term goal is to evaluate the predictive value of stress-immune-inflammatory responses to later health outcomes. Fifteen women reporting rape were compared with 16 control participants. Serum stress hormones, proinflammatory cytokines, acute phase proteins, functional assays, and lymphocyte subsets were measured in blood samples. Women reporting rape had higher cytotoxic cells, lower B lymphocyte counts, higher proinflammatory biomarkers, and decreased lymphocyte proliferation compared to the control group. This finding suggests that rape produces activation of the innate immunity and suppression of some aspects of adaptive immunity. If these immune changes persist, they may contribute to the pathophysiology of long-term health sequelae by provoking chronic inflammation and decreased cellular immunocompetence.     

Balance sheets of early boomers: are they different from pre-boomers?

Nationally representative data are used to compare the magnitude, composition, and distribution of accumulated wealth of early boomers (born between 1946 and 1957) and pre-boomers (born between 1934 and 1945) at the same life cycle stage (ages 44–45, occurring in 1989 for pre-boomers and in 2001 for early boomers). Early boomers have accumulated greater mean wealth than pre-boomers at the same age, however median wealth did not change and net worth among lower-middle wealth groups declined. Multivariate analysis identified demographic change among those in the wealth distribution tails that indicates the increasing importance of education and race as predictors of wealth.

New Ways to Promote Proenvironmental Behavior: Expanding and Evaluating Motives for Environmentally Responsible Behavior

This article contends that while striving to promote environmentallyresponsible behavior, we have focused attention too narrowly on just two classes of motives. There is a need to expand the range of motives available to practitioners and to provide a framework within which motives can be evaluated for both their immediate and long-term effectiveness. The article then examines a strategy for promoting environmentally responsible behavior that has significant potential. This strategy is based on a particular form of motivation called intrinsic satisfaction. Nine studies are reviewed that have outlined the structure of intrinsic satisfaction. A key theme discussed is the human inclination for competence. This fundamental human concern is shown to have both a general form and a resource-specific version.     

The Negotiation of Child Care and Employment Demands Among Low-Income Parents

Low-income working mothers face significant child care challenges. These challenges are particularly salient in an era of welfare reform, when welfare recipients are under increased pressure to find a job. The current study examines how child care demands are negotiated for an urban sample of low-income mothers. The sample includes a racially and ethnically diverse group of 57 respondents with and without welfare experience who are mothering children under 13 years of age and working in entry-level jobs. Findings suggest that respondents seek arrangements that are affordable, convenient, and safe, and informal arrangements may be most compatible with convenience and cost considerations. Informal care is not universally available, however, andmay be less reliable. Implications for child care policy are discussed.