Do stepping-stone jobs exist? Early career paths in the medical profession

In the Netherlands, students who want to become a medical specialist have to enrol in a training program which is in limited supply. During the search for a position as trainee (or “junior medical specialist”), they may accept a temporary job as a medical assistant. We use a micro data set to investigate whether such work experience increases the probability of becoming junior medical specialist. To deal with selectivity, we simultaneously model the transitions from unemployment to trainee, from unemployment to medical assistant, from medical assistant to trainee and from medical assistant to unemployment. We find that a job as medical assistant helps to become a medical specialist. Received: 27 July 2000/Accepted: 31 January 2001 All correspondence to Gerard J. van den Berg. Responsible editor: John F. Ermisch.     

Land Use Regulation and Welfare

We evaluate the effect of land use regulation on the value of land and on welfare. Our estimates are based on a decomposition of the effects of regulation into three components: an own‐lot effect, which reflects the cost of regulatory constraints to the owner of a parcel; an external effect, which reflects the value of regulatory constraints on one's neighbors; a supply effect, which reflects the effect of regulated scarcity of developable land. Using this decomposition, we arrive at a novel strategy for estimating a plausibly causal effect of land use regulation on land value and welfare. This strategy exploits cross‐border changes in development, prices, and regulation in regions near municipal borders. Our estimates suggest large negative effects of regulation on the value of land and welfare in these regions.     

Leader evaluations after performance feedback: The role of follower mood

Team and organizational failures can negatively impact leadership perceptions, as followers tend to attribute performance outcomes to leadership. The current study explores how follower mood moderates this effect. In two experiments, the first with students (N = 132) and the second with a sample of the working population (N = 229), we show that performance information has a weaker effect on leadership evaluations when the follower is in a positive mood as compared with a negative mood. In addition, we show that this moderation effect holds for performance information about the team as well as the leader. We discuss how these findings extend the cognitive follower-centric perspective on leadership by acknowledging affective influences and explore several counter-intuitive implications of these findings.     

Can a leader be seen as too ethical? The curvilinear effects of ethical leadership

Ethical leadership predicts important organizational outcomes such as decreased deviant and increased organizational citizenship behavior (OCB). We argued that due to the distinct nature of these two types of employee behaviors, ethical leadership decreases deviance in a linear manner (i.e., more ethical leadership leading to less deviance), but we expected ethical leadership to reveal a curvilinear relationship with respect to OCB. Specifically, we expected that, at lower levels, ethical leadership promotes OCB. However, at high levels, ethical leadership should lead to a decrease in these behaviors. We also examined a mechanism that explains this curvilinear pattern, that is, followers' perceptions of moral reproach. Our predictions were supported in three organizational field studies and an experiment. These findings offer a better understanding of the processes that underlie the workings of ethical leadership. They also imply a dilemma for organizations in which they face the choice between limiting deviant employee behavior and promoting OCB.     

Umbrella for research into Human Resource Development (HRD)

This paper explores Thailand's ‘sufficiency economy’ (SE) philosophy and its impact on human resource development (HRD). The paper highlights the current attempts to achieve sustainable development, especially after the economic crisis of 1997. The philosophy introduces a great shift of conceptual thinking on the general development and administration in the country. This paper examines the importance of the SE philosophy and discusses its impact on HRD in Thailand at different levels of the society.     

Clustering with or without the approximation

We study algorithms for clustering data that were recently proposed by Balcan et al. (SODA’09: 19th Annual ACM-SIAM Symposium on Discrete Algorithms, pp. 1068–1077, 2009a) and that have already given rise to several follow-up papers. The input for the clustering problem consists of points in a metric space and a number k, specifying the desired number of clusters. The algorithms find a clustering that is provably close to a target clustering, provided that the instance has the “(1+α,ε)-property”, which means that the instance is such that all solutions to the k-median problem for which the objective value is at most (1+α) times the optimal objective value correspond to clusterings that misclassify at most an ε fraction of the points with respect to the target clustering. We investigate the theoretical and practical implications of their results. Our main contributions are as follows. First, we show that instances that have the (1+α,ε)-property and for which, additionally, the clusters in the target clustering are large, are easier than general instances: the algorithm proposed in Balcan et al. (SODA’09: 19th Annual ACM-SIAM Symposium on Discrete Algorithms, pp. 1068–1077, 2009a) is a constant factor approximation algorithm with an approximation guarantee that is better than the known hardness of approximation for general instances. Further, we show that it is NP-hard to check if an instance satisfies the (1+α,ε)-property for a given (α,ε); the algorithms in Balcan et al. (SODA’09: 19th Annual ACM-SIAM Symposium on Discrete Algorithms, pp. 1068–1077, 2009a) need such α and ε as input parameters, however. We propose ways to use their algorithms even if we do not know values of α and ε for which the assumption holds. Finally, we implement these methods and other popular methods, and test them on real world data sets. We find that on these data sets there are no α and ε so that the dataset has both (1+α,ε)-property and sufficiently large clusters in the target solution. For the general case where there are no assumptions about the cluster sizes, we show that on our data sets the performance guarantee proved by Balcan et a. (SODA’09: 19th Annual ACM-SIAM Symposium on Discrete Algorithms, pp. 1068–1077, 2009a) is meaningless for the values of α,ε for which the data set has the (1+α,ε)-property. The algorithm nonetheless gives reasonable results, although it is outperformed by other methods.     

Cohort Quantum as a Function of Time-dependent Period Quantum for Non-repeatable Events

The paper discusses translation formulae for time-dependent cohort and period quantum for non-repeatable events. Cohort quantum expressions are investigated for two cases: one in which period quantum, and another in which the sum of the period rates decreases linearly with time. In both cases the assumption is that period tempo does not change. Sufficient conditions are given for the situation in which the cohort quantum simply equals the period quantum measured at the time when the cohort reaches the mean age of the period schedule of age-specific rates, given that the period rate sum is a polynomial function of time. The paper takes up an issue which was unresolved in the article ‘Translation formulae for non-repeatable events’, which appeared in the July 1994 issue of Population Studies.     

A multi-city epidemic model

Some analytical results are given for a model that describes the propagation of a disease in a population of individuals who travel between n cities. The model is formulated as a system of 2n 2 ordinary differential equations, with terms accounting for disease transmission, recovery, birth, death, and travel between cities. The mobility component is represented as a directed graph with cities as vertices and arcs determined by outgoing (or return) travel. An explicit formula that can be used to compute the basic reproduction number, {\cal R}_0 , is obtained, and explicit bounds on {\cal R}_0 are determined in the case of homogeneous contacts between individuals within each city. Numerical simulations indicate that {\cal R}_0 is a sharp threshold, with the disease dying out if {\cal R}_0 1 .