Influence of behavioural tactics on recruitment and reproductive trajectory in the kittiwake

Many studies have provided evidence that, in birds, inexperienced breeders have a lower probability of breeding successfully. This is often explained by lack of skills and knowledge, and sometimes late laying dates in the first breeding attempt. There is growing evidence that in many species with deferred reproduction, some prebreeders attend breeding places, acquire territories and form pairs. Several behavioural tactics assumed to be associated with territory acquisition have been described in different species. These tactics may influence the probability of recruiting in the breeding segment of the population, age of first breeding, and reproductive success in the first breeding attempt. Here we addressed the influence of behaviour ('squatting') during the prebreeding period on demographic parameters (survival and recruitment probability) in a long-lived colonial seabird species: the kittiwake. We also investigated the influence of behaviour on reproductive trajectory. Squatters have a higher survival and recruitment probability, and a higher probability of breeding successfully in the first breeding attempt in all age-classes where this category is represented. The influence of behaviour is mainly expressed in the first reproduction. However, there is a relationship between breeding success in the first occasion and subsequent occasions. The influence of breeding success in the first breeding attempt on the rest of the trajectory may indirectly reflect the influence of behaviour on breeding success in the first occasion. The shape of the reproductive trajectory is influenced by behaviour and age of first breeding. There is substantial individual variation from the mean reproductive trajectory, which is accounted for by heterogeneity in performance among individuals in the first attempt, but there is no evidence of individual heterogeneity in the rate of change over time in performance in subsequent breeding occasions     

Beheimatungsprozesse begleiten — ein Werkstattbericht

Supporting processes of belonging in supervision and coachingThe contemporary employee has to cope with frequent changes. Not only does he lose his familiar environment, he also has to find ways to familiarize himself with new places and to develop a fresh sense of belonging. This process can be understood and facilitated by interpreting the German concept of “Heimat“ as something we have to create ourselves. First experiences demonstrate the usefulness of this approach in coaching processes.     

Expected sample moments of concomitants of selected order statistics

In this paper, the task of determining expected values of sample moments, where the sample members have been selected based on noisy information, is considered. This task is a recurring problem in the theory of evolution strategies. Exact expressions for expected values of sums of products of concomitants of selected order statistics are derived. Then, using Edgeworth and Cornish-Fisher approximations, explicit results that depend on coefficients that can be determined numerically are obtained. While the results are exact only for normal populations, it is shown experimentally that including skewness and kurtosis in the calculations can yield greatly improved results for other distributions.     

A MODEL OF "FAMILY FAIRNESS" AND ITS IMPLICATIONS FOR DEBT NEUTRALITY

Evidence suggests that a signcant proportion, though by no means all, of bequests is equally divided among the beneficiaries. This is inconsistent with standard models of bequests, which predict that equal division should occur only by chance. This paper proposes a modified model incorporating "family fairness" as well as utilitarianism as an influence on behavior. Various implications for debt neutrality are analyzed.     

Picking the Winners: Politician vs. Voter Predictions of Two Controversial Ballot Measures

Abstract Both politicians and voters were asked to predict outcomesof two Oregon ballot measures in 1982. As expected, politicians'predictions always were closer to the mark than voters' were.Further, voters showed stronger signs of wishful thinking (the"Looking-Glass effect") in their predictions than did politicians.Using published preelection polls apparently improved politicians'accuracy in 1982, as well as voters' accuracy in a separate1984 survey. No other sources of data improved predictive accuracy.Findings have implications for theories of representative governmentand are consistent with a new theory of public opinion.     

Reconciling commodities and personal relations in industrial society

Conclusions I began this article with Colin Campbell's lament about the productionist bias in sociology and the related point that most sociologists concerned with consumption have ignored private meanings and small-scale structures in favor of public meanings and large-scale structures. This article calls attention to and builds on an emerging alternative approach to what happens after production, using an understanding of the social nature of objects that springs from Marcel Mauss's distinction between gifts and commodities.Mauss's model directs attention to the conflict in industrial societies between the two realms of commodity exchange and gift exchange, which I have cast as the conflict between the world of work and the world of family, and as the contrast between commodities and possessions. Thus, the model directs attention to the fact that objects are not simply transformed in production and displayed in consumption. However important these facts may be for understanding objects and society, they do not exhaust the important ways that people experience, use, and think about the objects that surround them. In particular, Mauss's model throws into relief the problematic nature of the objects that surround us and that we use in our social relations. And in doing so it directs attention to the ways that people try to reconstruct and redefine those objects by transforming them into personal possessions. This transformation makes objects acquired as commodities suitable for gift transactions, and hence suitable for the key task of recreating social relationships and social identities, the task of creating, not merely defining, who we are and how we are related to each other.Although the Maussian model addresses many of the links between people in the worlds of work and the home, and many of the ways that objects are part of these links, I am concerned here primarily with the ways that people can appropriate commodities in the process of purchase: shopping. This concern with shopping points out the social significance of retail trade, which I take to include advertising and shopping. This is not simply a passive conduit between production and consumption. Instead, it is an important point at which objects begin to leave the realm of work, commodities, and commodity relations and enter the realm of home, possessions, and gift relations. Shopping is an ubiquitous activity in industrial society and one that is highly significant culturally: we spend vast amounts of time, energy, money, and attention on it. Doubtless part of the reason for this is utilitarian, for we need to buy to live, but it would be foolish to reduce the significance of shopping to some combination of the need of individuals to acquire in order to survive and the need of companies to generate demand in order to profit. Thus, retail trade needs to be seen as well as a set of relations and transactions between seller and buyer that define and are defined by the objects and services involved, their history, and their future. My focus on purchasing food in supermarkets has the advantage of throwing into relief the problem of appropriation, because of the impersonality of object and social relations in large, self-service supermarkets. However, the very extremity of this example can create a false impression. As I noted, in other forms of shopping the social relations between buyer and seller, like the social identity of objects, can be more personal. This personality can be real, as when buyer and seller know each other or where the object is hand-made or even unique. Alternatively, it can be more purely symbolic, as when the selling company touts itself or its employees as friendly and caring or where the manufacturer advertises the personal nature of its commodities. In some cases, indeed, the manufacturing or trading company can present itself in such a way that the company itself becomes the person with whom the purchaser transacts. In addition, because of the focus on the appropriation of commodities in purchasing, I have touched only briefly on production and the world of work more generally. As does life at home, so life at work involves the transaction of objects and labor. Relations at work, then, will shape and be shaped by the nature of what is transacted. Co-workers who transact things that are more clearly stamped with their own identity, as among service workers and craft producers, will likely have more personal relations with fellow workers than will those who transact things that are themselves relatively impersonal, as in assembly-line production. This variability in the objects and relations at work suggests that people will have diverse understandings of work, and hence of manufactured objects more generally, which will affect the need they feel to appropriate commodities. In all, though, the point of this article is simple. People use objects to create and recreate personal social identities and relationships, and in industrial capitalist societies these objects are likely to be produced and purchased as commodities and understood as manufactures in Miller's sense. Our experience with and understanding of the production and sale of objects will affect the way we use them in transactions that create and recreate social identity and relationship, and will affect our understanding of the social identities and relationships that are created and recreated. Thus, the objects that people use in social relationships mediate between realms of economy and society, between the public realms where those objects are produced and distributed, and the private realms where those objects are transacted as part of social reproduction. The fact of this mediation and its effects on people's understanding of objects and social relations deserve careful attention.

---

     

An analytic method for randomized trials with informative censoring: Part 1

Consider a randomized trial in which time to the occurrence of a particular disease, say pneumocystis pneumonia in an AIDS trial or breast cancer in a mammographic screening trial, is the failure time of primary interest. Suppose that time to disease is subject to informative censoring by the minimum of time to death, loss to and end of follow-up. In such a trial, the censoring time is observed for all study subjects, including failures. In the presence of informative censoring, it is not possible to consistently estimate the effect of treatment on time to disease without imposing additional non-identifiable assumptions. The goals of this paper are to specify two non-identifiable assumptions that allow one to test for and estimate an effect of treatment on time to disease in the presence of informative censoring. In a companion paper (Robins, 1995), we provide consistent and reasonably efficient semiparametric estimators for the treatment effect under these assumptions. In this paper we largely restrict attention to testing. We propose tests that, like standard weighted-log-rank tests, are asymptotically distribution-free -level tests under the null hypothesis of no causal effect of treatment on time to disease whenever the censoring and failure distributions are conditionally independent given treatment arm. However, our tests remain asymptotically distribution-free -level tests in the presence of informative censoring provided either of our assumptions are true. In contrast, a weighted log-rank test will be an -level test in the presence of informative censoring only if (1) one of our two non-identifiable assumptions hold, and (2) the distribution of time to censoring is the same in the two treatment arms. We also extend our methods to studies of the effect of a treatment on the evolution over time of the mean of a repeated measures outcome, such as CD-4 count.     

A non-parametric index of tracking

SUMMARY A two-sample version of the non-parametric index of tracking for longitudinal data introduced by Foulkes and Davis is described. The index is based on a multivariate U -statistic, and provides a measure of the stochastic ordering of the underlying growth curves of the samples. The utility of the U -statistic approach is explored with two applications related to growth curves and repeated measures analyses.