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     

MAKING MULTICULTURALISM RELEVANT FOR MAJORITY CULTURE GRADUATE STUDENTS*

The revised accreditation standards for marriage and family therapy programs (Manual on Accreditation, 1988) require that the curriculum reflect an emphasis on “issues of gender and ethnicity as they relate to marital and family therapy” (p. 13). Training approaches that are described in the professional literature tend to emphasize an understanding of ethnic minorities while deemphasizing the trainee's own ethnic and cultural roots. As such, training lacks dynamic integrity for the white, middle-class trainee. This paper describes a rationale for addressing the ethnic and cultural background of all family therapy trainees and provides training activities to accomplish this end.     

Can recessions be predicted?

Can recessions, or serious turning points in general, be predicted? Or do forecasters tend to assume that the future will continue as an extension of the near past. Theoretical evidence and practical observations tend to support the hypothesis that forecasters are unduly influenced by current events and feel that booms or contractions in the economy will continue for much longer than they actually do. In the opinion of the authors this is a serious shortcoming of a good majority of those involved with forecasting who do not seem to be learning from experience. The basic question which the authors consider in this article is whether it is possible to avoid either of the two extremes. If this is possible, they argue that this will allow economic signs to be correctly interpreted, which ‘quite often can give clear indications of forthcoming changes in the level of economic activity’.     

Strategies for planning

In recent years there has been a good deal of discussion amongst planning specialists and academics about the gap which exists between the theory of planning as set out in journals and textbooks, and the practice of planning in private and public organizations. Planners are continually complaining about the resistance to planning by top management and operating managers in divisions and departments.In this article the author aims to produce a reconciliation between theory and practice and to discuss what alternative strategies are open to planners in devising planning systems for their organizations.He suggests that the problem has its origin in the fact that corporate planning theory was first developed by management scientists as a total systems approach. Corporate planners have failed to sell an integrated planning system either as programme budgeting or as corporate planning. Research suggests that a management team can only adopt and implement a comprehensive planning system in very special circumstances, e.g. when the organization's survival is threatened, a new management team has been appointed and the staff of the organization are ready to accept radical change.In normal circumstances the planner is wrong to advocate a ‘root and branch’ solution. He must diagnose the planning needs of the organization and his objective must be not merely to establish a particular planning procedure but rather to discover how he can best improve the quality of management decisions.Recent studies on strategy formation indicate that the introduction of a formal planning procedure is only a partial answer to the problem of improving the quality of management decisions.The paper reviews various approaches to planning and considers how they relate to organizations with different strategic problems, with differing organization structures and various management styles.     

The sample monomode and an associated test for discrete monomodality

Abstract

The notions of (sample) mean, median and mode are common tools for describing the central tendency of a given probability distribution. In this article, we propose a new measure of central tendency, the sample monomode, which is related to the notion of sample mode. We also illustrate the computation of the sample monomode and propose a statistical test for discrete monomodality based on the likelihood ratio statistic.     

Age-period-cohort analysis: an illustration of the problems in assessing interaction in one observation per cell data

This paper discusses the specific problems of age-period-cohort (A-P-C) analysis within the general framework of interaction assessment for two-way cross-classified data with one observation per cell. The A-P-C multiple classification model containing the effects of age groups (rows), periods of observation (columns), and birth cohorts (diagonals of the two-way table) is characterized as one of a special class of models involving interaction terms assumed to have very specific forms. The so-called A-P-C identification problem, which results from the use of a particular interaction structure for detecting cohort effects, is shown to manifest itself in the form of an exact linear dependency among the columns of the design matrix. The precise relationship holding among these columns is derived, as is an explicit formula for the bias in the parameter estimates resulting from an incorrect specification of an assumed restriction on the parameters required to solve the normal equations. Current methods for modeling A-P-C data are critically reviewed, an illustrative numerical example is presented, and one potentially promising analysis strategy is discussed. However, gien the large number of possible sources for error in A-P-C analyses, it is strongly recommended that the results of such analyses be interpreted with a great deal of caution.     

Moment expressions and summary statistics for the complete and truncated weibull distribution

Traditionally, the moments of the Weibull distribution have been calculated using the standard Weibull (Johnson and Kotz, 1970) . This article will expand on that idea and cover the truncated cases for the standard Weibull distributions. Also, the same techniques used for the standard form will be used to derive the moment expressions for the three-parameter complete and truncated Weibull distributions. The summary statistics are then calculated from the moment expressions. Weibull moments involve the gamma and incomplete gamma functions.