卫生技术评估与循证医学：我们研究的是什么？

本期《健康价值》（《Value in Health》特刊刊载了五个国家技术评估（Technology Assessment，TA）方面的文章，主要介绍了这些国家技术评估的范围，如何制定相关决策以及技术评估手段如何支持这些决策。每篇文章的着眼点各不相同。这些文章将有助于读者更好地了解这些国家的决策制定过程和技术评估方法。若将这些文章综合参考的话，则可以获得更大的启示。     

Knowledge positions in high-tech markets: Trajectories,standards, strategies and true innovators

Essential patents refer to patents that are indispensable in order to make any product that complies with a technological standard. Portfolios of essential patents have often been used to indicate the strategic value of a firm's knowledge. We propose a range of alternative indicators based on a firm's position in patent citation network. Using a historical narrative and the actual licencing payments for the 3G W-CDMA standard in mobile telecommunications as a reference, we find that our alternative indicators provide better indicators for firms' knowledge positions and their long-term impact on technological change. Our proposed indicators can also be applied in markets that are not based on standards, and may not only be valuable to scholars but also to practitioners. Our findings also raise some concern over technology inclusion processes at standards bodies, and we recommend policy makers to consider our proposed method in order to critically look at these processes.     

Measuring the Incidence of Over- and Undereducation

We deploy the unique opportunity of a dataset of Flemish school leavers to measure the incidence of over- and undereducation on the basis of the six applied measures in the literature. The incidence of overeducation in the first job after leaving school ranges from only 8% to 51%, undereducation ranges from 3% to 21%. While 66% is overeducated on the basis of at least one measure, only 3% is overeducated on the basis of every measure. Mismatch correlations range from 5% to 82%. Also the categories in terms of gender, educational level and region of residence with the highest likelihood of being overeducated depend on the measure. These findings clearly underline the weakness of the literature on this subject. However, measuring overeducation in different ways enables to derive some alternative concepts. Genuine overeducation amounts to about 20%. The incidence of over- and undereducation is both attributed to qualification inflation and deflation, and a credential gap. Finally, about 80% of the incidence of overeducation is classified as being structural.     

Statistical Issues in fMRI for Brain Imaging

Functional magnetic resonance imaging is a technique developed in the last decade and used in the fields of cognitive psychology and neuroscience, among others, to study the processes underlying the working of the human brain. In this paper we examine some of the statistical issues in functional magnetic resonance imaging for brain research. We start by giving a brief introduction to the physics of magnetic resonance imaging. Using a psychological experiment as a case study, we then describe questions of design and statistical analysis. The data obtained from functional magnetic resonance imaging studies are of a highly complex nature, displaying both spatial and temporal correlation, as well as high levels of noise from different sources. Given this, the scope for statistics is vast, and is not limited to simple analysis of the data, once collected.     

Slipping Anchor? Testing the Vignettes Approach to Identification and Correction of Reporting Heterogeneity

We propose tests of the two assumptions under which anchoring vignettes identify heterogeneity in reporting of categorical evaluations. Systematic variation in the perceived difference between any two vignette states is sufficient to reject vignette equivalence. Response consistency - the respondent uses the same response scale to evaluate the vignette and herself - is testable given sufficiently comprehensive objective indicators that independently identify response scales. Both assumptions are rejected for reporting of cognitive and physical functioning in a sample of older English individuals, although a weaker test resting on less stringent assumptions does not reject response consistency for cognition.     

Decision aid reliance: Modeling the effects of decision aid reliability and pressures to perform on reliance behavior

We investigate the effects of decision aid reliability and pressure to perform on decision aid reliance. A total of 403 students took part in a four (pressures to perform: one through four) by five (decision aid reliability: 50%, 60%, 70%, 80% and 90%) between-participants experiment. We test two competing models of decision aid reliance behavior: pressure-induced rationality and pressure arousal theory. Additionally, we introduce a general model of reliance on a decision aid. We find that pressure arousal theory predominantly explains decision aid reliance behavior at all but the highest level of decision aid reliability tested in this study (90%). Our results indicate that there are reliance peaks across the reliability levels as more pressure to perform is applied, and that continually increasing pressures can eventually lead to decreased, rather than increased, reliance.     

AN INTEGRATED ECONOMETRIC MODEL OF THE CANADIAN LIVESTOCK-FEED SECTOR*

Canadian econometric studies dealing with the livestock-feed sector have tended to concentrate on individual commodities, or on a particular component of the market equilibrium process. In this article an integrated model of the sector is presented which depicts the nature of commodity interactions both at the consumer level and the producer level. The feed sector was conceptualized primarily in terms of derived demand. The model contained a total of 82 equations, of which 64 were related to the livestock subsystem. The estimated model was subsequently used for predicting the impact of changes in selected instrumental variables on the livestock-feed sector.
Les dernières etudes économétriques canadiennes traitant du pâturage se sont concentrées sur les produits séparés on sur un composé particulier répondant au besoin commercial. Cet article présents un modèle intégré du secteur montrant la nature des actions réciproques entrc les produits au niveau du consommateur et du producteur. Le secteur pâturage est expliqué en fonction de la demande. Le modèle contenait 82 équations, 64 desquelles se rapportaient àľélevage; par conséquent le modèle est employé pour prédire ľinfluence dans les pâturages de changements opérés sur les composants choisis.     

Just keep it simple: a field experiment on fundraising letters

• This paper studies how the use of a colour picture in fundraising letters affect response rates and the amount donated in a fundraising campaign. Envelopes, with a full colour picture were tested against envelopes, without a picture in a controlled field experiment at a national religious charity in the Netherlands. Letters (89 937) were sent out to planned as well as incidental donors in four experimental groups. Results show that packages with more graphics yield lower donations, because both response rates are lower and the amount donated per letter is lower. We interpret this finding from donor aversion against high fundraising costs.

Copyright © 2007 John Wiley & Sons, Ltd.     

Ethno-cultural diversity and organizational effectiveness: a field study

This paper examines the relationship between ethno-cultural diversity and attitudinal and non-attitudinal measures of organizational performance in a field setting. Data were collected from ninety-eight respondents in seven branches of a leading Canadian bank. As compared to culturally homogeneous branches, the culturally heterogeneous branches experienced lower levels of absenteeism and achieved higher productivity and financial profitability despite their lower scores on job satisfaction, organizational commitment and workplace coherence, and higher rates of turnover. These relationships were moderated by age, job tenure, organizational position, children's age, location of education and previous employment, birthplace and education level.