形成性评价（Formative Assessment）的本质及其对教与学的影响

长期以来,很多学者一直倡导指导教学的评价,即通过评估学生需求和监测其学习进展,适当地设计学习顺序,调整教学策略,改良学习计划,以便有效地促进学习目标的完成。本研究调查了形成性评价在美国中学科学课中的实施情况,并分析其对学生学习进步的影响。研究表明,教师都在努力使用形成性评价来指导教学,而学生取得的成绩各不相同。     

Widely linear estimation for multisensor quaternion systems with mixed uncertainties in the observations

The optimal widely linear state estimation problem for quaternion systems with multiple sensors and mixed uncertainties in the observations is solved in a unified framework. For that, we devise a unified model to describe the mixed uncertainties of sensor delays, packet dropouts and uncertain observations by using three Bernoulli distributed quaternion random processes. The proposed model is valid for linear discrete-time quaternion stochastic systems measured by multiple sensors and it allows us to provide filtering, prediction and smoothing algorithms for estimating the quaternion state through a widely linear processing. Simulation results are employed to show the superior performance of such algorithms in comparison to standard widely linear methods when mixed uncertainties are present in the observations.     

The dispersion of technology and income in Europe: Evolution and mutual relationship across regions

The first part of this article explores whether convergence has occurred in technology and income across EU regions during the period 1990-2002. The second part evaluates whether these two processes of convergence are related to each other. With respect to the first question, we find that all R&D indicators and patents have converged among regions during the 1990s and this has ran parallel to a real convergence in income per capita levels. Regarding the second question, we have identified a strong relationship between the distribution of technology indicators and the distribution of regional income in Europe. Our main result is that convergence in business R&D leads to convergence in patents, which in turn leads to convergence in income per capita. Although, we identify a role for government R&D and higher education spending in this process, the policy implications for these two variables are less clear.     

Physical activity and school recess time: differences between the sexes and the relationship between children's playground physical activity and habitual physical activity

The aims of this study were: (1) to observe participation in moderate-to-vigorous physical activity (MVPA) during school recess periods; (2) to determine the relative importance of physical activity during recesses to overall daily physical activity; and (3) to examine differences in physical activity between the sexes during unstructured recess periods. The participants were 22 school children (10 boys, 12 girls) aged 8 - 10 years (mean = 8.9, s = 0.7) in the third and fourth grades. Daily totals for the physical activity variables were calculated by summing the values for each hour of 14 h of physical activity measurements (08:00 to 22:00 h). Recess times (minutes) were as follows: morning 10:30 to 11:00 h and afternoon 15:30 to 16:00 h. We did not differences between boys and girls in daily total accelerometer counts or the overall time spent in MVPA. However, girls were significantly (P < 0.05) more involved (38%) in MVPA during recess time than boys (31%). Participation in MVPA during recess contributes significantly more (P < 0.05) for girls (19%) than boys (15%) to the total amount of physical activity suggested by international health-related physical activity guidelines, while the percentage of time engaged in MVPA during recess time at school accounts for a small amount of the daily MVPA (6% for boys and 8% for girls). The results of this study suggest that school recess time is an important setting to promote MVPA and contributes to daily physical activity in young children, especially in girls.     

Bayesian Learning from Arts Goods? – A Comment

This comment considers the applicability of the Cyert and DeGroot model of adaptive utility in modeling consumer choice behavior with respect to arts goods. An illustration of the consumer’s choice behavior on expenditure shares is simulated as a simple Markov chain. This is followed by a discussion of policy implications regarding the pricing and subsidization of arts goods.     

Learning-by-Consuming and the Dynamics of the Demand and Prices of Cultural Goods

The major distinctive feature of cultural goods is that consumers must learn how to consume them, implying that preferences should be modelled as intertemporally dependent. The canonical model in the literature uses a habit formation analogy. In this paper, we discuss in detail, though in the simplest setup, a consistent preference structure for that model. Then, we derive the implications for the dynamics of two aggregate equilibrium models, a fixed price model and a flexible price model. The learning-by-consuming behaviour is characterised by a preference structure displaying bounded adjacent complementarity in the demand for the cultural good. This implies that there will be short run complementarity between the stocks of culture and financial wealth and that the adjustment of the demand for cultural goods, or of their relative price, will have some inertia. In the exogenous price model, we find that increases in income will raise the long run demand for cultural goods while increases in the relative price will decrease it. In the endogenous price model, an increase in the supply of cultural goods will imply an initial undershooting of the price of cultural goods followed by an upward transition process. Our results seem to be consistent with the empirical results on the demand for cultural goods and seem to offer an explanation for the Baumol and Bowen paradox.JEL Classification: Z1, E21Earlier versions of this paper have been presented at the 1st Conference of the Sociedade Portuguesa de Investigação em Economia (SPiE, 1997) and at the Xth Conference of the Association for Cultural Economics International, 1998, Barcelona.     

Preferences need no inferences, once again: germinal elements in the public perceptions of genetically modified foods in Colombia

This paper explores the public perceptions of genetically modified foods in Colombia in a phase considered germinal: the topic was too novel at the time of research. The analysis covers media, informal conversations, and the word associations made by a sample of residents in the city of Bogotá. The results show that the public capability of associating with the topic, even intuitively, is due to the availability of culture themes, the primary categories that help conceptual elaborations, and the construction of common-sense theories. Three themes are proposed: natural/artificial, tradition/change, and health/disease. It is argued that cultural themes are not only cognitive, but also affectively laden entities, which explains the evaluative force expressed by social beliefs. Acknowledging the relevance of the non-attitude thesis, the author suggests that people associate novel objects with latent cultural meanings, explaining why words, images, and metaphors are readily available in elaborating social knowledge.