Efficiency with Endogenous Population Growth

In this paper, we generalize the notion of Pareto efficiency to make it applicable to environments with endogenous populations. Two efficiency concepts are proposed: ℘‐efficiency and 𝒜‐efficiency. The two concepts differ in how they treat potential agents that are not born. We show that these concepts are closely related to the notion of Pareto efficiency when fertility is exogenous. We prove a version of the first welfare theorem for Barro–Becker type fertility choice models and discuss how this result can be generalized. Finally, we study examples of equilibrium settings in which fertility decisions are not efficient, and we classify them into settings where inefficiencies arise inside the family and settings where they arise across families.     

制浆新工艺——喷爆蒸煮制浆法

喷爆蒸煮制浆可认为是改良的化学机械制浆技术 .本文以芦苇为原料 ,采用相同的设备对喷爆蒸煮制浆工艺与内蒙古华章造纸厂的碱法制浆工艺进行了对比试验 ,并就试验结果进行了分析比较 ,进而为喷爆蒸煮制浆技术的应用提供了可供参考的数据     

THE COLOR OF THE UNDERGRADUATE EXPERIENCE AND THE OCCUPATIONAL ATTAINMENT OF BLACKS AND WHITES: Evidence from Longitudinal Data

This study examines the impact of attendance at colleges with higher black enrollment on occupational attainment. The unique multipopulation LISREL models focus on blacks and whites, specify income and occupational self-direction as distinct dimensions of labor market accomplishment, and adjust for the possible confounding influence of college selectivity and precollege self-appraisals. Data from the NLS-72, augmented by selectivity and black enrollment data from other sources, are utilized. Findings largely support the hypothesis of within-race parity in occupational attainment. Black enrollment exerts nonsignificant effects on income among blacks and occupational self-direction in both races and slightly enhances income among whites.     

Farmer Knowledge and Risk Analysis: Postrelease Evaluation of Herbicide-Tolerant Canola in Western Canada

The global controversy regarding the use of genetically modified (GM) crops has proved to be a challenge for "science-based" risk assessments. Although risk analysis incorporates societal perspectives in decision making over these crops, it is largely predicated on contrasts between "expert" and "lay" perspectives. The overall objective of this study is to explore the role for farmers' knowledge, and their decade-long experience with herbicide-tolerant (HT) canola, in the risk analysis of GM crops. From 2002 to 2003, data were collected using interviews ( n = 15) and mail surveys ( n = 370) with farmers from Manitoba and across Canada. The main benefits associated with HT canola were management oriented and included easier weed control, herbicide rotation, and better weed control, whereas the main risks were more diverse and included market harm, technology use agreements (TUAs), and increased seed costs. Benefits and risks were inversely related, and the salient factor influencing risk was farmer experiences with HT canola volunteers, followed by small farm size and duration using HT canola. These HT volunteers were reported by 38% of farmers, from both internal (e.g., seedbank, farm machinery, etc.) and external (e.g., wind, seed contamination, etc.) sources, and were found to persist over time. Farmer knowledge is a reliable and rich source of information regarding the efficacy of HT crops, demonstrating that individual experiences are important to risk perception. The socioeconomic nature of most risks combined with the continuing "farm income crisis" in North America demonstrates the need for a more holistic and inclusive approach to risk assessment associated with HT crops and, indeed, with all new agricultural technology.     

An experimental investigation of imprecision attitude and its relation with risk attitude and impatience

We report in this article the result of three experiments on risk, ambiguity, and time attitude. The first two differed by the population considered (students vs. general population) while the third one used a different protocol and concerned students and portfolio managers. We find quite a lot of heterogeneity at the individual level. Of principal interest was the elicitation of risk, time, and ambiguity attitudes and the relationship among these (model free) measures. We find that on the student population, there is essentially no correlation. A non-negligible fraction of the population behaves in an extremely cautious manner in the risk and ambiguity domain. When we drop this population from the sample, the correlation between our measures is also non-significant. We also raise three questions linked to measurement of ambiguity attitudes that come out from our data sets.     

Changes in professional vision in the context of practice

In initial teacher education, it is a challenge to foster the development of teaching skills proximal to classroom action. In this study, the impact of a combined practical and theoretical university-based term on preservice teachers’ professional vision is investigated by a video-based approach to supervising their knowledge acquisition and assessing their learning outcomes. Participants were N = 109 preservice teachers attending a 5-month theory practice term guided through video-based courses about effective teaching and learning. We measured their changes in professional vision using the video-based tool Observer. Our results show that preservice teachers positively change their professional vision during the theory practice term, especially if they show low entry levels at the beginning. Their notes on the observed teaching lessons illustrate these changes.