Construction of Fuzzy Control Charts Based on Weighted Possibilistic Mean

The problem of constructing control charts for fuzzy data has been considered in literature. The proposed transformation approaches and direct fuzzy approaches have their advantages and disadvantages. The representative values charts based on transformation methods are often recommended in practical application. For representing a fuzzy set by a crisp value, the weight of importance of the members assigned with some membership levels in a fuzzy set should be considered, and the possibility theory can be employed to deal with such problem. In this article, we propose to employ the weighted possibilistic mean (WPM), weighted interval valued possibilistic mean (WIVPM) of fuzzy number as a sort of representative values for the fuzzy attribute data, and establish new fuzzy control charts with WPM and WIVPM. The performance of the charts is compared to the existing fuzzy charts with a fuzzy c-chart example via newly defined average number of inspection for variation of control state.     

Perspective of practical biological control and population theories

We have not yet had sufficient theoretical explanation for successful biological control in which a key pest is controlled after an introduction of natural enemies. I compare here real features of successful biological control and theoretical host–parasitoid population models to reduce the gap between theory and practice. I first review the historical interaction between classical biological control projects and theoretical population models. Second, I consider the importance of host refuges in host–parasitoid population dynamics as concerns the mechanisms of low and stable host density. The importance of density–dependent parasitism through parasitoid reproduction in multivoltine host–parasitoid systems and supplemental generalist natural enemies are also discussed. Finally, I consider the difference in tactics for classical biological control and for augmentation of natural enemies in annual crop systems. Received: December 20, 1998 / Accepted: January 15, 1999     

ATTRIBUTION ERROR IN ECONOMIC VOTING: EVIDENCE FROM TRADE SHOCKS

This article exploits the international transmission of business cycles to examine the prevalence of attribution error in economic voting in a large panel of countries from 1990 to 2009. We find that voters, on average, exhibit a strong tendency to oust the incumbent governments during an economic downturn, regardless of whether the recession is home‐grown or merely imported from trading partners. However, we find important heterogeneity in the extent of attribution error. A split sample analysis shows that countries with more experienced voters, more educated voters, and possibly more informed voters—all conditions that have been shown to mitigate other voter agency problems—do better in distinguishing imported from domestic growth. (JEL E3, E6)     

Covariate selection for estimating the causal effect of control plans by using causal diagrams

Summary. Consider a case where cause–effect relationships between variables can be described by a causal path diagram and the corresponding linear structural equation model. The paper proposes a graphical selection criterion for covariates to estimate the causal effect of a control plan. For designing the control plan, it is essential to determine both covariates that are used for control and covariates that are used for identification. The selection of covariates used for control is only constrained by the requirement that the covariates be non-descendants of a treatment variable. However, the selection of covariates used for identification is dependent on the selection of covariates used for control and is not unique. In the paper, the difference between covariates that are used for identification is evaluated on the basis of the asymptotic variance of the estimated causal effect of an effective control plan. Furthermore, the results can be also described in terms of a graph structure.     

Demography of an island population of the lizard,Eumeces okadae, on Miyake-jima, Izu Islands

Summary The demography of the lizardEumeces okadae was studied for 4 years on Miyake-jima, in the Izu Islands, central Japan. Most males matured at 3 years of age with a mean snout-vent length of 77.5 mm. Females matured at 3–4 years with a mean SVL of 77.8 mm, and reproduced biennially thereafter. Growth continued after maturity with a decreasing rate. In females, annual growth was negligible in reproductive years, but resumed markedly in non-reproductive years. Clutch size increased with SVL and was used to construct a fecundity schedule. Population density (exclusive of hatchlings) was estimated to be ca. 4000 individuals/ha in August, an exceptionally high density for lizards. Before introduction of the weasel onto Miyake-jima, low predation pressure had allowedE. okadae to maintain a high population density. Estimated annual survival rates were 36% for hatchlings, 56% for yearlings, 80% for 2-year-olds, 63% for adult males and 76% for adult females. The cohort generation time (6.95 years) was so long that theE. okadae population can be characterized by a combination of low natality and slow turnover.     

Social work for vulnerable and marginalized people during COVID-19 in Japan

During the Coronavirus disease pandemic (COVID-19), working conditions became increasingly difficult for social workers, as they had to deal with new challenges and added workloads. This study describes the difficulties faced by social workers of the Self-Reliance Support System in Japan and clarifies the solution for each difficulty while conducting their duties to support vulnerable people during COVID-19. To this end, we conducted an open-ended questionnaire survey and an interview survey. The data were analyzed using qualitative coding. The results showed that the difficulties faced in consultation support work included supporting hitherto socially invisible groups such as sole traders and foreigners. Social workers also faced an ethical dilemma, as they could not provide support to clients who “did not try to solve their problems” or for whom “interventional attempts did not lead to counseling support” and who only sought benefits at the risk of becoming isolated and impoverished. Following this, consultants collaborated to resolve such difficulties while maximizing the use of various local resources. The study's findings clarify that it would be effective to understand the difficulties faced by social workers to obtain hints toward their resolution.