Age-specific dynamic labor demand and human capital investment

To study the optimal age-specific labor demand and human capital investment at the firm level we extend the standard dynamic labor demand model by introducing ‘age’ as a second dynamic variable and distinguish between two types of workers: ‘low skilled’ and ‘high skilled’. Applying an age-structured optimal control model we derive qualitative features of the optimal age-specific hiring and training effort. For the case of a linear revenue and production function we prove that firms do not anticipate changes in adjustment costs in their optimal decisions. This result no longer holds if a nonlinear revenue or production function is considered.     

The ‘science’ and ‘practice’ of HRM in small firms

This paper looks at the ‘science’ and ‘practice’ of human resource management in small firms. While there is growing evidence that the practice of human resource management in small firms is characterized by informality, there is less evidence about the science, or explaining why this is the case. We look to writing on strategic human resource management, which has at its heart the resource based view of the firm, for possibilities offered to understanding the science of human resource management in small firms.     

Institutional investors, antitakeover defenses and success of hostile takeover bids

In this study we investigate the question of whether institutional investors enhance or reduce efficiency in the market for corporate control. In particular, given unequivocal evidence that target stockholders gain in successful takeover bids, we investigate the impact of institutional ownership in target firms on the adoption of the type of antitakeover defense as well as the outcome of takeover bids. We find that target firms are more likely to adopt value-reducing antitakeover defenses and successfully thwart takeover bids when a higher percentage of target common stock is owned by ‘pressure-indeterminate’ investors (investment counsel firms in particular). On the other hand, the probability of a successful takeover rises with the ownership of both ‘pressure-sensitive’ and ‘pressure-resistant’ investors. The above findings support the view that institutional investors do not play a homogeneous role in the market for corporate control.     

Linear-quadratic approximation, external habit and targeting rules

We examine the linear-quadratic approximation of nonlinear dynamic stochastic optimization problems. A discrete-time version of Magill [1977a. A local analysis of N-sector capital accumulation under uncertainty. Journal of Economic Theory 15(2), 211–219] is generalized to models with forward-looking variables paying special attention to second-order conditions. This is the ‘large distortions’ case in the literature. We apply the approach to monetary policy in a DSGE model with external habit in consumption. We then develop a condition for ‘target-implementability’, a concept related to ‘targeting rules’. Finally, we extend the approach to a comparison between cooperative and non-cooperative equilibria in a two-country model and show that the ‘small distortions’ approximation is inappropriate for this exercise.     

Towards a common understanding of the differences between purchasing, procurement and commissioning in the UK public sector

This paper recognises that commissioning has now become an important term in the lexicon of UK public policy but the term ‘commissioning’ is taking on a different meaning than that traditionally used within the purchasing and supply management community. The frequent inter-changeability of the terms ‘commissioning’, ‘procurement’ and ‘purchasing’ is now causing confusion and means different things to different people. Therefore the academic community needs to help practitioners understand the differences and implications. A document analysis of various UK Central Government departments’ commissioning frameworks was used to establish the key themes and compare commissioning, procurement and purchasing. This paper discusses the similarities and differences, and argues that commissioning is different from procurement, but that commissioning offers major opportunities for Procurement practitioners to make a strategic contribution.     

The system of towns with spatial public goods

In this paper, we introduce a model of ‘spatial public goods’, whose provision costs depend on the size of the benefit area. It is assumed that there are many developers providing spatial public goods in their towns. Each developer chooses the area size of his/her town and the quality of its spatial public good so as to maximize profit, taking the market price system as given. Each consumer chooses the level of the public good, and hence the town that supplies it, so as to maximize his/her utility. We show that the competitive equilibrium allocation of this economy is efficient.     

A Hotelling model with a ceiling on the stock of pollution

Environmental agreements such as the Kyoto Protocol aim to stabilize the amount of carbon in the atmosphere, which is mainly caused by the burning of nonrenewable resources such as coal. We characterize the solution to the textbook Hotelling model when there is a ceiling on the stock of emissions. We consider both increasing and decreasing demand for energy. We show that when the ceiling is binding, both the low-cost nonrenewable resource and the high-cost renewable resource may be used jointly. A key implication is that if energy demand were to decline in the long run, we may supplement energy supply through ‘clean’ renewables to meet the environmental standard, but then revert back to using only ‘dirty’ fossil fuels in the future when the ceiling has become non-binding. That is, the much heralded societal ‘transition’ to clean energy resources may be short-lived.     

Management of a capital stock by Strotz's naive planner

The capital management problem posed by R.H. Strotz is analyzed for the case of the ‘naive’ planner who fails to anticipate changes in his own preferences. By imposing progressively stronger restrictions on the primitives of the problem – namely, the discounting function, the utility index function, and the investment technology – the planner's behavior is characterized first as the solution to an ordinary differential equation and then via explicit formulae. Inasmuch as these characterizations leave the discounting function essentially unrestricted, the theory can accommodate, in particular, decision makers who discount time according to the hyperbolic and ‘quasi-hyperbolic’ curves used in applied work and said to be supported by psychological studies. Comparative statics of the model are discussed, as are extensions of the analysis to allow for credit constraints, limited foresight, and partial commitment.     

Benchmark priors for Bayesian model averaging

In contrast to a posterior analysis given a particular sampling model, posterior model probabilities in the context of model uncertainty are typically rather sensitive to the specification of the prior. In particular, ‘diffuse’ priors on model-specific parameters can lead to quite unexpected consequences. Here we focus on the practically relevant situation where we need to entertain a (large) number of sampling models and we have (or wish to use) little or no subjective prior information. We aim at providing an ‘automatic’ or ‘benchmark’ prior structure that can be used in such cases. We focus on the normal linear regression model with uncertainty in the choice of regressors. We propose a partly non-informative prior structure related to a natural conjugate g-prior specification, where the amount of subjective information requested from the user is limited to the choice of a single scalar hyperparameter g_0j. The consequences of different choices for g_0j are examined. We investigate theoretical properties, such as consistency of the implied Bayesian procedure. Links with classical information criteria are provided. More importantly, we examine the finite sample implications of several choices of g_0j in a simulation study. The use of the MC³ algorithm of Madigan and York (Int. Stat. Rev. 63 (1995) 215), combined with efficient coding in Fortran, makes it feasible to conduct large simulations. In addition to posterior criteria, we shall also compare the predictive performance of different priors. A classic example concerning the economics of crime will also be provided and contrasted with results in the literature. The main findings of the paper will lead us to propose a ‘benchmark’ prior specification in a linear regression context with model uncertainty.     

The latin model of welfare: Do ‘insertion contracts’ reduce long-term dependence?

This paper aims to present an assessment of the welfare policies implemented in most South European countries. Welfare programs in these countries try to combine a basic level of economic protection and measures favoring life and labor skills (‘insertion benefits’) of low-income households. We focus on a specific program set up with the twofold strategy of cash and ‘insertion benefits’ (Madrid's IMI) and, more precisely, on the so-called ‘insertion projects’, consisting in a gradual mix of job search assistance, training and subsidized jobs. We evaluate the effects of these ‘insertion projects’ on welfare recidivism and the duration of off-welfare spells using propensity score-matching methods. Our results suggest that propensity score estimators appear to reduce selectivity due to non-random participation. Both recidivism rates as well as the duration of off-welfare spells suggest potentially successful interventions.     

Inside the queue:: hypercongestion and road pricing in a continuous time–continuous place model of traffic congestion

This paper develops a continuous-time–continuous-place dynamic economic model of traffic congestion, based on car-following theory. The model integrates two archetype congestion technologies used in the economics literature: ‘static flow congestion’ and ‘dynamic bottleneck congestion.’ With endogenous departure times and a bottleneck along the route, ‘hypercongestion’ arises as a dynamic equilibrium phenomenon on the upstream road segment. Congestion tolls based on an intuitive dynamic and space-varying generalization of the standard Pigouvian tax rule can hardly be improved upon. A naïve application of a toll schedule based on Vickrey's bottleneck model performs much worse and reduces welfare in the numerical model.     

The Delphi technique as a forecasting tool: issues and analysis

This paper systematically reviews empirical studies looking at the effectiveness of the Delphi technique, and provides a critique of this research. Findings suggest that Delphi groups outperform statistical groups (by 12 studies to two with two ‘ties’) and standard interacting groups (by five studies to one with two ‘ties’), although there is no consistent evidence that the technique outperforms other structured group procedures. However, important differences exist between the typical laboratory version of the technique and the original concept of Delphi, which make generalisations about ‘Delphi’ per se difficult. These differences derive from a lack of control of important group, task, and technique characteristics (such as the relative level of panellist expertise and the nature of feedback used). Indeed, there are theoretical and empirical reasons to believe that a Delphi conducted according to ‘ideal’ specifications might perform better than the standard laboratory interpretations. It is concluded that a different focus of research is required to answer questions on Delphi effectiveness, focusing on an analysis of the process of judgment change within nominal groups.     

Self-organized criticality in evolutionary systems with local interaction

This paper studies a stylized model of local interaction where agents choose from an ever increasing set of vertically ranked actions, e.g. technologies. The driving forces of the model are infrequent upward shifts (‘updates’), followed by a rapid process of local imitation (‘diffusion’). Our main focus is on the regularities displayed by the long-run distribution of diffusion waves and their implication on the performance of the system. By integrating analytical techniques and numerical simulations, we come to the following two main conclusions. (1) If non-coordination costs are sufficiently high, the system behaves critically, in the sense customarily used in physics. (2) The performance of the system is optimal at the frontier of the critical region. Heuristically, this may be interpreted as an indication that (performance-sensitive) evolutionary forces induce the system to be placed ‘at the edge of order and chaos’.     

When does coordination pay?

In a continuous-time model of two symmetric open economies, with a floating exchange rate, we find that the pay-off to macroeconomic policy coordination depends systematically on how heterogeneous is their inflation experience. While monetary policy coordination improves welfare in handling a common rate of underlying inflation, it exacerbates the ‘time consistency’ problem arising when there are differences (as is illustrated diagrammatically). Since the principle of ‘certainty equivalence’ applies to time-consistent policy in linear quadratic models, we are also able to give a stochastic interpretation of the deterministic results.     

Economic dynamics of reservoir sedimentation management: Optimal control with singularly perturbed equations of motion

We analyze the economic dynamics of reservoir sedimentation management using the hydrosuction-dredging sediment-removal system. System dynamics depend on two interdependent hydraulic processes evolving at different rates. The accumulation of water impounded in the reservoir evolves on a ‘fast’ time scale, while the loss of water storage capacity to trapped sediments evolves on a ‘slow’ time scale. We formulate a multidimensional optimal control problem with singularly perturbed equations of motion to accommodate the disparate time scales. We apply singular perturbation methods to approximate (via polynomial series expansion) a ‘slow’ manifold reducing multi-dimensional solution space to the single-dimensional subspace confining long-term dynamics.     

A theoretical comparison of the opportunity and gravity models

This paper compares the opportunity model with the gravity model from a theoretical view- point. First, based on a reexamination of Schneider's model, the ‘perceived opportunity model’ is proposed as a generalization of Schneider's model. Second, the similarity of the opportunity and gravity models is examined. In particular the condition of the opportunity model behaving like the gravity model is presented. Third, the difference of these models is investigated in terms of certain general model-theoretic properties. The behavioral ‘sensitivity’ of each model to spatial configuration changes is revealed by these properties.     

Developing a typology of organisational forms of cooperative purchasing

This paper develops a typology for purchasing groups. In the typology, five main forms of cooperative purchasing are distinguished based on seven main dimensions. The forms are positioned in a matrix according to two distinguishing dimensions. These two dimensions are the ‘influence by all members on the group activities’ and the ‘number of different group activities’. Underlying the two-dimensional matrix, there are five other dimensions that do not distinguish all forms from each other, but further detail the forms of cooperative purchasing. The typology can serve as a guideline for purchasing groups when a suitable organisational form needs to be chosen. In a suitable form, the dimensions of a group fit together. For all groups, it is recommended to find this best fit. This is something in which the typology may help. The paper concludes by emphasising the importance of clearly defining and positioning studied forms, because different forms imply different research models and have different advantages, disadvantages, and critical success factors.     

Implementing property tax reforms in Bangalore: an actor-network perspective

Many municipal governments in developing countries are experiencing serious difficulties in dealing with the rapid growth of population in cities. Catalysed through processes of globalisation, the growth of cities, especially the so-called ‘mega-cities’, has not been matched by investments in infrastructure like roads and power due to the inability of local government organizations to collect adequate revenues from sources like property tax. Recognizing these difficulties, agencies such as the Asian Development Bank have initiated systems for property tax reforms in a number of Asian cities, including Bangalore. In this paper, we discuss the story of this reform process drawing upon the actor-network perspective on translations. We argue that such a perspective helps to go beyond studying innovation processes through the lens of ‘technology diffusion’, and provides a more interesting and insightful perspective of ‘technology translation’.     

Theoretical tests of the rational expectations hypothesis in economic dynamical models

This paper examines different theoretical stability tests of infinite-horizon rational expectations equilibria. These ‘tests’ have different status: two of them express that the considered equilibrium is ‘isolated’ [neither (non-sunspot) equilibria (test 1) nor (well-behaved) sunspot equilibria exist in a neighbourhood (test 2)] and two of them are learning criteria [either standard ‘evolutive learning’ (test 3) or game-theoretical ‘eductive’ learning (test 4)]. Surprisingly, these four tests select the same steady state equilibria in the class of one-dimensional one-step-forward looking economic models. The extension of this equivalence theorem to n-dimensional and then more complex systems is discussed.     

民营医院医疗虚拟团队整体的质量协调机制研究

医疗质量是民营医院的核心竞争力,受到虚拟团队分散性和动态性影响,民营医院医疗虚拟团队医疗质量协调管理是非常必要的。鉴于虚拟团队的动态性,本文构建了基于动态合约的质量协调管理机制,从医院与成员、医院评价小组与成员、团队管理者与成员等三个角度,分合作初、合作中、合作完成三个阶段,为民营医院医疗虚拟团队的质量协调管理提供一种较好的解决方案。