A cross-cultural test of the situational bias hypothesis : The israeli scene

The major aim of this study was to test the commonly held assumption, within the Israeli educational context, that the relatively poor mean performance of disadvantaged students on conventional ability tests is due, in part, to extraneous situational factors, systematically disadvantageous to their test performance. To that end, two controlled field experiments were conducted on independent samples of N = 288 and N = 48 elementary school pupils, respectively. The first experiment centered on the interaction between sociocultural group characteristics and each of two situational factors, namely, test atmosphere and examiner status, in affecting ability test performance. The second experiment explored the effects of test atmosphere per se on the nonverbal ability test scores of disadvantaged pupils. On the whole, this research provides evidence inconsistent with the situational bias hypothesis and does not support the assumption that disadvantaged children's ability test scores can be substantially improved by manipulating test atmosphere conditions. In view of the evidence showing that situational variables do not significantly bias testing results in favor of one group over another, it follows that current educational evaluation policies in Israel, relying heavily on the standardized ability tests results of disadvantaged groups, need not be changed.     

A galling aphid with extra life-cycle complexity: Population ecology and evolutionary considerations

Summary In most gall-forming aphids, only the fundatrix is able to induce a gall on the host plant. InSmynthurodes betae Westw. (and a few other species), F₂ descendants emerge from the mother gall and induce their own, morphologically different galls. This constitutes an added complexity to the already very complex life cycle of gall-forming aphids. We investigated the ecology ofS. betae on marked trees and shoots at four sites in Israel. Gall initiation, gall distribution and density, and temporal changes in clone size within the galls were investigated during two consecutive years. We discuss the possibility that the two-gall life cycle evolved from the typical one-gall system of most gall aphids, and the possible selective advantage of this added complexity in the life-history strategy of gall aphids. Although the total reproductive output ofS. betae is not higher than in related species with a single gall per life cycle, there seems to be an advantage in the subdivision of each aphid clone into several galls, thus reducing the risk of the accidental extinction of the clone (genotype) by environmental factors, including parasites and predators.     

Stochastic comparison of processes generated by random interruptions of monotone functions and related results

Many stochastic processes considered in applied probability models, and, in particular, in reliability theory, are processes of the following form: Shocks occur according to some point process, and each shock causes the process to have a random jump. Between shocks the process increases or decreases in some deterministic fashion. In this paper we study processes for which the rate of increase or decrease between shocks depends only on the height of the process. For such processes we find conditions under which the processes can be stochastically compared. We also study hybrid processes in which periods of increase and periods of decrease alternate. A further result yields a stochastic comparison of processes that start with a random jump, rather than processes in which there is at the beginning some random delay time before the first jump.Supported by NSF Grant DMS 9303891.     

Evaluating the effects of full-time vs part-time educational programs for the gifted: affective outcomes and policy considerations

This study evaluates the effects of student participation in two different educational programs/settings for the gifted, i.e., full time homogeneous classes vs mixed ability classes (with a part-time extension program), on a variety of affective outcome. Data on academic self-concept, test anxiety, achievement motivation, perceptions of giftedness, school attitudes, and satisfaction with school were gathered on a sample of 1020 Israeli gifted elementary school children in grades 4–6. Analyses of the data pointed to a less positive personal-social profile in students partaking in special full-time homogeneous classes, compared to their mainstreamed counterparts, as evidenced by lower evaluative anxiety, higher academic self-concept, and more positive labeling in the former setting. However, compared to their mainstreamed counterparts in mixed ability classes, students in special homogeneous classes for the gifted held more favorable attitudes towards various facets of the school/classroom environment (school atmosphere, level of instruction, teacher-student relations, teacher characteristics) and were also more satisfied with school in general when compared to their gifted counterparts partaking in mixed ability classes. The tradeoff between a more positive perception of the school environment and less effective personal-social adjustment for students in special gifted classes should be given due consideration by program planners and evaluators in any cost-benefit analysis of educational programs for gifted students.     

Line Balancing in Parallel M/M/1 Lines and Loss Systems as Cooperative Games

We consider production and service systems that consist of parallel lines of two types: (i) M/M/1 lines and (ii) lines that have no buffers (loss systems). Each line is assumed to be controlled by a dedicated supervisor. The management measures the effectiveness of the supervisors by the long run expected cost of their line. Unbalanced lines cause congestion and bottlenecks, large variation in output, unnecessary wastes and, ultimately, high operating costs. Thus, the supervisors are expected to join forces and reduce the cost of the whole system by applying line‐balancing techniques, possibly combined with either strategic outsourcing or capacity reduction practices. By solving appropriate mathematical programming formulations, the policy that minimizes the long run expected cost of each of the parallel‐lines system, is identified. The next question to be asked is how to allocate the new total cost of each system among the lines' supervisors so that the cooperation's stability is preserved. For that sake, we associate a cooperative game to each system and we investigate its core. We show that the cooperative games are reducible to market games and therefore they are totally balanced, that is, their core and the core of their subgames are non‐empty. For each game a core cost allocation based on competitive equilibrium prices is identified.     

Labor Migration,Remittances and Household Income: A Comparison between Filipino and Filipina Overseas Workers1

The major purpose of the research is to examine gender differences in patterns of labor market activity, economic behavior and economic outcomes among labor migrants. While focusing on Filipina and Filipino overseas workers, the article addresses the following questions: whether and to what extent earnings and remittances of overseas workers differ by gender; and whether and to what extent the gender of overseas workers differentially affects household income in the Philippines. Data for the analysis were obtained from the Survey of Households and Children of Overseas Workers (a representative sample of households drawn in 1999–2000 from four major “labor sending” areas in the Philippines). The analysis focuses on 1,128 households with overseas workers. The findings reveal that men and women are likely to take different jobs and to migrate to different destinations. The analysis also reveals that many more women were unemployed prior to migration and that the earnings of women are, on average, lower than those of men, even after controlling for variations in occupational distributions, country of destination, and sociodemographic attributes. Contrary to popular belief, men send more money back home than do women, even when taking into consideration earnings differentials between the genders. Further analysis demonstrates that income of households with men working overseas is significantly higher than income of households with women working overseas and that this difference can be fully attributed to the earnings disparities and to differences in amount of remittances sent home by overseas workers. The results suggest that gender inequal‐     

A Three‐step Method for Choosing the Number of Bootstrap Repetitions

This paper considers the problem of choosing the number of bootstrap repetitions B for bootstrap standard errors, confidence intervals, confidence regions, hypothesis tests, p‐values, and bias correction. For each of these problems, the paper provides a three‐step method for choosing B to achieve a desired level of accuracy. Accuracy is measured by the percentage deviation of the bootstrap standard error estimate, confidence interval length, test's critical value, test's p‐value, or bias‐corrected estimate based on B bootstrap simulations from the corresponding ideal bootstrap quantities for which B=∞. The results apply quite generally to parametric, semiparametric, and nonparametric models with independent and dependent data. The results apply to the standard nonparametric iid bootstrap, moving block bootstraps for time series data, parametric and semiparametric bootstraps, and bootstraps for regression models based on bootstrapping residuals. Monte Carlo simulations show that the proposed methods work very well.     

When Less is More: Lessons from 25 Years of Attempting to Maximize the Effect of Each (and Often Only) Therapeutic Encounter

The three main findings of studies conducted by Hoyt, Rosenbaum, and myself during the years 1986–1990 at the Kaiser Permanente Medical Group, were

• 1 . Single session is the most common length of psychotherapy.
• 2 . The first session in psychotherapy is potentially the most therapeutic and often has the greatest influence on the outcome of therapy.
• 3 . Single session therapy (SST) is the most cost‐effective mode of therapy.

The fact that less is very often better in psychotherapy is by now one of the most validated and consistent findings in evidence‐based psychotherapy research. We now think of it as a very common, very useful way of conducting therapy, employing many different approaches and methods to address a wide range of presenting problems. In retrospect, 25 years later, I believe that the essence of single session therapy is still about being present in each and every session as a whole. The goal has always been to make the most of every therapeutic session, whether seeing a client only once or over a long period of time. In a personal communication in 1978, Haley (in Talmon, 1990) predicted that a ‘single interview could become the standard for estimating how long and how successful therapy should be.’ This article explains why it didn't happen.