Attrition presents a challenge for research, especially when it affects groups differentially. The present study used the strategy proposed by Cook and Campbell (1979) to investigate attrition in a community-based literacy program. The relationship of attrition to person-centered and program-centered variables, and the interactions between person-centered and program-centered variables were examined in 287 Head Start families. Thus, data from this program were used to illustrate methods for examining attrition and determine its effects. This examination revealed differences among the intervention groups in the pattern of attrition. There were interactions between intervention program-centered characteristics and person-centered characteristics of the participants that could affect the validity of the study and limit the generalizability of the results. Suggestions for dealing with these problems and preventing attrition are discussed. 相似文献
Using the methods of asymptotic decision theory asymptotically optimal for translation and scale families as well as for certian nonparmetric families. Moreover, two new classes of nonlinear rank tests are introduced. These tests are designed for detecting either “ omnibus alternatives ” or “ one sided alternatives of trend ”. Under the null hypothesis of randomness all tests are distribution - free. The asymptotic distributions of the test statistics are derived under contiguous alternatives. 相似文献
A therapy project was developed for pathological gambling patients and, within a three year period, more than 60 gamblers were studied and treated. Diagnostic evaluation was made according to DSM-III. In addition to individual and family therapy, we designed a voluntary group setting. In this report, we concentrate first on the development of group work, then on some psychodynamic hypotheses about the personality of the gambler. We also try to show the correspondence between these hypotheses and the group process. Pathological gambling is seen as an attempt at self-healing and a strategy of conflict-solving; the slot machine, as an inanimate object, offers a temporary symbiosis with clear limitations; the gambling will come to a guaranteed end, either when all of the money is lost, or when gaming ends at night. Finally, we list some recommendations for the treatment of gamblers in group therapy.This research was supported by the Ärztliche Psychologische Beratungsstelle für Studierende der Universität Göttingen, Chairman: Prof. E. Sperling, M.D.Since one author (J.H.) worked alone in the first period of the project, passages referring to this period are written in the first person singular.This article is an extension of the special issue on Gambling in Europe edited by Iver Hand, M.D. 相似文献
We are concerned with a situation in which we would like to test multiple hypotheses with tests whose p‐values cannot be computed explicitly but can be approximated using Monte Carlo simulation. This scenario occurs widely in practice. We are interested in obtaining the same rejections and non‐rejections as the ones obtained if the p‐values for all hypotheses had been available. The present article introduces a framework for this scenario by providing a generic algorithm for a general multiple testing procedure. We establish conditions that guarantee that the rejections and non‐rejections obtained through Monte Carlo simulations are identical to the ones obtained with the p‐values. Our framework is applicable to a general class of step‐up and step‐down procedures, which includes many established multiple testing corrections such as the ones of Bonferroni, Holm, Sidak, Hochberg or Benjamini–Hochberg. Moreover, we show how to use our framework to improve algorithms available in the literature in such a way as to yield theoretical guarantees on their results. These modifications can easily be implemented in practice and lead to a particular way of reporting multiple testing results as three sets together with an error bound on their correctness, demonstrated exemplarily using a real biological dataset. 相似文献
We investigate risk attitudes when the underlying domain of payoffs is finite and the payoffs are, in general, not numerical. In such cases, the traditional notions of absolute risk attitudes, that are designed for convex domains of numerical payoffs, are not applicable. We introduce comparative notions of weak and strong risk attitudes that remain applicable. We examine how they are characterized within the rank-dependent utility model, thus including expected utility as a special case. In particular, we characterize strong comparative risk aversion under rank-dependent utility. This is our main result. From this and other findings, we draw two novel conclusions. First, under expected utility, weak and strong comparative risk aversion are characterized by the same condition over finite domains. By contrast, such is not the case under non-expected utility. Second, under expected utility, weak (respectively: strong) comparative risk aversion is characterized by the same condition when the utility functions have finite range and when they have convex range (alternatively, when the payoffs are numerical and their domain is finite or convex, respectively). By contrast, such is not the case under non-expected utility. Thus, considering comparative risk aversion over finite domains leads to a better understanding of the divide between expected and non-expected utility, more generally, the structural properties of the main models of decision-making under risk.
Although knowledge is attributed a high societal value, its traditional ‘production’ in academia as well as its traditional ‘consumption’ in education have increasingly become problematic. Austrian politics have launched a rather unconventional political steering instrument to solve this problem: Sparkling Science. Based on the equal involvement of pupils and scientists in research projects, this program aims to create ‘sparks of enthusiasm’ as well as ‘sparks of innovation’ between academia and education. We inquire into the effects of this political steering instrument on the level of individual actors. Drawing on qualitative data from a case study, our analyses identify a structural composition that alters the two explicit objectives, which are: To increase pupil’s enthusiasm for science and to stimulate innovative research based on multiple perspectives. 相似文献
Investment decisions are often characterized by uncertainty, irreversibility, and timing flexibility. We use a binomial model
to investigate the interdependencies of effects from profit taxation and both an option to delay and an option to abandon
on investment decisions. We show that increasing the tax rate can lead to paradoxical tax effects, i.e. it may foster an investor’s
willingness to invest. By contrast, if we abstract from the abandonment option, such paradoxical effects cannot be identified.
Hence, we show that paradoxical tax effects can be caused by an abandonment option. Our results are helpful for investors
facing risky investment opportunities and for improving typical valuation approaches. 相似文献