The role of negative associations and trust in risk perception of new hydrogen systems

In this study the moderating role of trust and negative affective associations on the inverse relationship between risk and benefit judgements is investigated. A survey (N = 406) was held in the Netherlands on the public perception of new hydrogen systems, during the time that a demonstration project with hydrogen buses was being undertaken. The data of the survey show that for the group of respondents with a negative evaluation of trust in actors involved, an inverse relationship between risk and benefit judgements can be observed. Furthermore, for the group of respondents that had elicited negative affective spontaneous associations with hydrogen in general, the inverse relationship was also found. The inverse relationship between risk and benefit judgements was not observed in the group not making these spontaneous associations. The strongest negative correlation between risk and benefit judgements was found for those who had a negative evaluation of trust and had elicited negative affective spontaneous associations. In all cases the general affective evaluation of hydrogen systems was the mediating factor in this inverse relationship between risk and benefit judgements. These findings provide evidence for the moderating role of trust and negative affective associations on the observed inverse relationship between perceived benefit and perceived risk.     

Pollution control and the Ramsey problem

Pollution is an inevitable by-product of production and is only gradually dissolved by the environment. It can be reduced by producing less and by cleaning up the environment, but neither occur when they are left to the market. Cleaning activities and the optimal emission charges increase with the stock of pollutants. When one allows for pollution of the environment in the classical Ramsey problem, the capital stock is less than in the market outcome and a fortiori less than under the golden rule. The analysis distinguishes between stock and flow externalities arising from pollution. An increase in impatience can lead to more capital accumulation, even though this leaves less room for current consumption.     

Scaling and institutionalization within agricultural innovation systems: the case of cocoa farmer field schools in Cameroon

The farmer field school (FFS) concept has been widely adopted, and such schools have the reputation of strengthening farmers’ capacity to innovate. Although their impact has been studied widely, what is involved in their scaling and in their becoming an integral part of agricultural innovation systems has been studied much less. In the case of the Sustainable Tree Crops Programme in Cameroon, we investigate how a public–private partnership (PPP) did not lead to satisfactory widespread scaling in the cocoa innovation system. We build a detailed understanding of the key dimensions and dynamics involved and the wider lessons that might be learned regarding complex scaling processes in the context of agricultural innovation systems. Original interview data and document analysis inform the case study. A specific analytical approach was used to structure the broad-based exploration of the qualitative dataset. We conclude that scaling and institutionalization outcomes were impeded by: the lack of an adaptive approach to scaling the FFS curriculum, limited investments and genuine buy-in by extension actors, a failure to adapt the management approach between the pilot and the scaling phase, and the lack of strategic competencies to guide the process. Our findings support suggestions from recent literature that pilots need to be translated and adapted in light of specific contextual and institutional conditions, rather than approached as a linear rolling-out process. These findings are relevant for the further spread of similar approaches commonly involved in multi-stakeholder scaling processes such as innovation platforms.     

Handling measurement issues and strategic directions in Kraljic''s purchasing portfolio model

Kraljic's purchasing portfolio model, which was introduced in 1983, still is the dominant approach in the profession. Contrary to the growing use of the Kraljic matrix, there are problems and unanswered questions with respect to measurement and strategic issues. Based on explorative case studies, the critique of Kraljic's model has been disputed and refuted to a large extent. This study describes the solutions of experienced practitioners to the problems which have been put forward in literature. The case studies point out which measurement methods are possible and which supplier strategies are feasible, including additional strategic movements of commodities within the matrix. The research findings indicate that there is no simple, standardized blue print for the application of the portfolio analysis. It requires reflecting on results, critical thinking and sophistication of purchasing management.     

Pollution,abatement and balanced growth

The analysis of endogenous growth models with pollution often concentrates on steady state trajectories, under the assumption that the steady state is in some sense stable. In the present note we provide examples showing that this issue should be dealt with carefully. We use the Rebelo Ak model augmented with a stock of pollutants causing a negative externality. It is found that optimal growth is not necessarily balanced (contrary to the outcome of the standard Rebelo model). Moreover, the existence of the externality may affect long run optimal growth rates.The author is grateful to an anonymous referee for comments. All remaining errors are the author's sole responsibility.     

Measuring Agreement in Ordered Rating Scales

Ordered rating scales are one of the most frequently used question formats in large-scale surveys. Analysts of the responses to such questions often find themselves in need of describing the degree of agreement (concentration, consensus) of the answers to such questions. For that purpose they commonly use standard deviations of the response distributions, or measures based on these (such as the coefficient of consensus defined by Granberg and Holmberg, 1988), or the coefficient of variability, etc. This paper demonstrates that such measures are inappropriate for this purpose because they misrepresent what they are supposed to measure: the `peakedness' of a distribution. As an alternative a measure of agreement A is proposed. This measure is a weighted average of the degree of agreement that exists in the simple component parts – layers – into which any frequency distribution can be disaggregated, and for which agreement can be expressed in a straightforward and unequivocal way.     

Bayesian modification indices for IRT models

Bayesian modification indices are presented that provide information for the process of model evaluation and model modification. These indices can be used to investigate the improvement in a model if fixed parameters are re-specified as free parameters. The indices can be seen as a Bayesian analogue to the modification indices commonly used in a frequentist framework. The aim is to provide diagnostic information for multi-parameter models where the number of possible model violations and the related number of alternative models is too large to render estimation of each alternative practical. As an example, the method is applied to an item response theory (IRT) model, that is, to the two-parameter model. The method is used to investigate differential item functioning and violations of the assumption of local independence.     

The Rise, Fall and Sustainability of Capital-Resource Economies

In debates about green accounting it is sometimes argued that a positive value of aggregate investments indicates that an economy is developing sustainably. Asheim (1994) and Pezzey (1994) have shown that this is wrong, using a version of the well-known Dasgupta–Heal economy (with one capital and one non-renewable resource stock) as a counterexample. Asheim's proof referred to the unproved assumptions that in such an economy a higher rate of time preference induces higher initial consumption and vice versa, and that "optimal" consumption is initially rising and then falling. Here we show that these assumptions do hold true under certain circumstances, thereby also proving some of Dasgupta and Heal's other conjectures about sustainability.     

Employers' recruitment behaviour and vacancy duration: an empirical analysis for the Dutch labour market

The functioning of labour markets from a demand-side perspective is examined. In particular, the determinants of vacancy duration are studied in the context of a model of employers' search behaviour. A model for the choice of the recruitment strategy at the start of the search process and the corresponding recruitment duration is developed in which allowance is made for different patterns of duration dependence for each recruitment strategy. This model is applied to data on employers' search behaviour in the Dutch labour market. It is found that employers prefer advertisements as the first recruitment channel when applicants are required to have work experience. Moreover, employers prefer to start searching via the labour exchange office when jobs in the secondary segment of the labour market have to be filled. It is also found that - when advertisements are used as the first recruitment strategy - employers need some time to acquire a pool of applicants and to select candidates from this pool. It is interesting as a contrast that applicants seem to be evaluated rather quickly if employers start searching via informal contacts.