Recent misconceptions about the "database search problem": a probabilistic analysis using Bayesian networks

This paper analyses and discusses arguments that emerge from a recent discussion about the proper assessment of the evidential value of correspondences observed between the characteristics of a crime stain and those of a sample from a suspect when (i) this latter individual is found as a result of a database search and (ii) remaining database members are excluded as potential sources (because of different analytical characteristics). Using a graphical probability approach (i.e., Bayesian networks), the paper here intends to clarify that there is no need to (i) introduce a correction factor equal to the size of the searched database (i.e., to reduce a likelihood ratio), nor to (ii) adopt a propositional level not directly related to the suspect matching the crime stain (i.e., a proposition of the kind 'some person in (outside) the database is the source of the crime stain' rather than 'the suspect (some other person) is the source of the crime stain'). The present research thus confirms existing literature on the topic that has repeatedly demonstrated that the latter two requirements (i) and (ii) should not be a cause of concern.

Unemployment vs. mismatch of talents: Reconsidering unemployment benefits

We develop an equilibrium search-matching model with risk-neutral agentsand two-sided ex-ante heterogeneity. Unemployment insurance has thestandard effect of reducing employment, but also helps workers to get a suitable job. The predictions of our simple modelare consistent with the contrasting performance of the labor market in Europeand US in terms of unemployment, productivity growth and wage inequality.To show this, we construct two fictitious economies with calibratedparameters which only differ by the degree of unemployment insurance andassume that they are hit by a common technological shock which enhancesthe importance of mismatch. This shock reduces the proportion of jobs whichworkers regards as acceptable in the economy with unemployment insurance(Europe). As a result, unemployment doubles in this economy.In the laissez-faire economy (US), unemployment remains constant,but wage inequality increases more and productivity grows less due to largermismatch. The model can be used to address a number of normative issues.

Costly search and design

Firms compete by choosing both a price and a design from a family of designs thatcan be represented as demand rotations. Consumers engage in costly sequential searchamong firms. Each time a consumer pays a search cost he observes a new offering. Anoffering consists of a price quote and a new good, where goods might vary in the extentto which they are good matches for the consumer. In equilibrium, only two design-styles arise: either the most niche where consumers are likely to either love or loathethe product, or the broadest where consumers are likely to have similar valuations. Inequilibrium, different firms may simultaneously offer both design-styles. We performcomparative statics on the equilibrium and show that a fall in search costs can lead tohigher industry prices and profits and lower consumer surplus. Our analysis is relatedto discussions of how the internet has led to the prevalence of niche goods and the"long tail" phenomenon.

Trade, migration and regional unemployment

We formulate a dynamic core-periphery model with frictions in the job matching process to study the interplay between trade costs, migration and regional unemploymentin the short- and long-run. We find that the spatial distribution of unemployment mirrors (inversely) the distribution of economic activities. Further, we highlight a contrast between the short-run and the long-run effects of trade-induced migration on regional unemployment. In particular, an inßow of immigrants from the periphery into the core reduces the unemployment gap in the short-run, but exacerbates unemployment disparities in the long-run.

Schumpeterian technology shocks

We analyze the labor market effects of neutral and investment-specific technologyshocks along the intensive margin (hours worked) and the extensive margin(unemployment). We characterize the dynamic response of unemploymentin terms of the job separation and the job finding rate. Labor market adjustmentsoccur along the extensive margin in response to neutral shocks, along theintensive margin in response to investment specific shocks. The job separationrate accounts for a major portion of the impact response of unemployment. Neutralshocks prompt a contemporaneous increase in unemployment because of asharp rise in the separation rate. This is prolonged by a persistent fall in thejob finding rate. Investment specific shocks rise employment and hours worked.Neutral shocks explain a substantial portion of the volatility of unemploymentand output; investment specific shocks mainly explain hours worked volatility.This suggests that neutral progress is consistent with Schumpeterian creative destruction,while investment-specific progress operates as in a neoclassical growthmodel.

Shocks and institutions in a job matching model

This paper explains the divergent behavior of European an US unemploymentrates using a job market matching model of the labor market with aninteraction between shocks an institutions. It shows that a reduction inTF growth rates, an increase in real interest rates, and an increase intax rates leads to a permanent increase in unemployment rates when thereplacement rates or initial tax rates are high, while no increase inunemployment occurs when institutions are "employment friendly". The paperalso shows that an increase in turbulence, modelle as an increase probabilityof skill loss, is not a robust explanation for the European unemploymentpuzzle in the context of a matching model with both endogenous job creationand job estruction.

Business cycles, unemployment insurance and the calibration of matching models

This paper theoretically and empirically documents a puzzle that arises when an RBC economy with a job matching function is used to model unemployment. The standard model can generate sufficiently large cyclical fluctuations in unemployment, or a sufficiently small response of unemployment to labor market policies, but it cannot do both. Variable search and separation, finite UI benefit duration, efficiency wages, and capital all fail to resolve this puzzle. However, either sticky wages or match-specific productivity shocks can improve the model's performance by making the firm's flow of surplus more procyclical, which makes hiring more procyclical too.

Equilibrium unemployment insurance

In this paper, we incorporate a positive theory of unemployment insuranceinto a dynamic overlapping generations model with search-matching frictionsand on-the-job learning-by-doing. The model shows that societies populatedby identical rational agents, but differing in the initial distributionof human capital across agents, may choose very different unemploymentinsurance levels in a politico-economic equilibrium. The interactionbetween the political decision about the level of the unemployment insuranceand the optimal search behavior of the unemployed gives rise to aself-reinforcing mechanism whichmay generate multiple steady-stateequilibria. In particular, a European-type steady-state with highunemployment, low employment turnover and high insurance can co-exist withan American-type steady-state with low unemployment, high employment turnoverand low unemployment insurance. A calibrated version of the model featurestwo distinct steady-state equilibria with unemployment levels and durationrates resembling those of the U.S. and Europe, respectively.

Job creation under liquidity constraints: The Spanish case

This paper shows that liquidity constraints restrict jobcreation even when labor markets are flexible. In a dynamicmodel of labor demand, I show that in an environment of imperfect capital and imperfect labor markets, firms usetemporary contracts to relax financial constraints. Evidence for the predictions of the model is presented using Spanish data from the CBBE (Central de Balances del Banco de España - Balance Sheet data from the Bank of Spain). It is shown that firms substitute temporary laborfor permanent one and use less debt as their financial position improves. In particular, it is rejected that Spanish firms operate in an environment of free capital markets and of no labor adjustment costs. The labor reform of 1984, which created temporary contracts, implied to some extent a relaxation of liquidity constraints.Accordingly, firms used these contracts more extensivelyand used less debt; however, as capital markets continueto be imperfect, permanent job creation continues to beslow. Consequently, relaxation of liquidity constraints should also be part of a job creation strategy.

When Preference Is Not Satisfied but the Individual Is: How Power Distance Affects Person-Job Fit

One aspect of person-job fit reflects congruence between personal preferences and job design; as congruence increases so should satisfaction. We hypothesized that power distance would moderate whether fit is related to satisfaction with degree of job formalization. We obtained measures of job-formalization, fit and satisfaction, as well as organizational commitment from employees (n = 772) in a multinational firm with subsidiaries in six countries. Confirming previous findings, individuals from low power-distance cultures were most satisfied with increasing fit. However, the extent to which individuals from high power-distance cultures were satisfied did not necessarily depend on increasing fit, but mostly on whether the degree of formalization received was congruent to cultural norms. Irrespective of culture, satisfaction with formalization predicted a broad measure of organizational commitment. Apart from our novel extension of fit theory, we show how moderation can be tested in the context of polynomial response surface regression and how specific hypotheses can be tested regarding different points on the response surface.

Optimal information transmission in organizations: Search and congestion

We propose a stylized model of a problem-solving organization whoseinternal communication structure is given by a fixed network. Problemsarrive randomly anywhere in this network and must find their way to theirrespective specialized solvers by relying on local information alone.The organization handles multiple problems simultaneously. For this reason,the process may be subject to congestion. We provide a characterization ofthe threshold of collapse of the network and of the stock of foatingproblems (or average delay) that prevails below that threshold. We buildupon this characterization to address a design problem: the determinationof what kind of network architecture optimizes performance for any givenproblem arrival rate. We conclude that, for low arrival rates, the optimalnetwork is very polarized (i.e. star-like or centralized ), whereas it islargely homogenous (or decentralized ) for high arrival rates. We also showthat, if an auxiliary assumption holds, the transition between these twoopposite structures is sharp and they are the only ones to ever qualify asoptimal.

Internet use by patients with psychiatric disorders in search for general and medical informations

BACKGROUND: Internet is commonly used by the general population, notably for health information-seeking. There has been little research into its use by patients treated for a psychiatric disorder. AIM: To evaluate the use of internet by patients with psychiatric disorders in searching for general and medical information. METHODS: In 2007, 319 patients followed in a university hospital psychiatric out-patient clinic, completed a 28-items self-administered questionnaire. RESULTS: Two hundred patients surveyed were internet users. Most of them (68.5%) used internet in order to find health-related information. Only a small part of the patients knew and used criteria reflecting the quality of contents of the websites consulted. Knowledge of English and private Internet access were the factors significantly associated with the search of information on health on Internet. CONCLUSIONS: Internet is currently used by patients treated for psychiatric disorders, especially for medical seeking information.

Downsizing, job insecurity and firm reputation

This paper studies how firms make layoff decisions in the presence of adverse shocks. In this uncertain environment, workers' expectations about their job security affect their on-the-job performance. This productivity effect on job insecurity forces firms to strike a balance between laying off redundant workers and maintaining survivors' commitment when deciding on the amount and timing of downsizing. This framework offers an explanation of conservative employment practices (such as zero or reduced layoffs) based on firms having private information about their future profits. High retention rates and wages can signal that the firm has a bright future, boosting workers' confidence. Moreover, the model provides clear predictions about when waves of downsizing will occur as opposed to one-time massive cuts.

A search theory of money and commerce with Neoclassical production

This paper advances a highly tractable model with search theoretic foundations for money and neoclassical growth. In the model, manufacturingand commerce are distinct and separate activities. In manufacturing,goods are efficiently produced combining capital and labor. In commerce,goods are exchanged in bilateral meetings. The model is applied to studythe effects of inßation on capital accumulation and welfare. With realisticparameters, inflation has large negative effects on welfare even though itraises capital and output. In contrast, with cash-in-advance, a deviceinformally motivated with bilateral trading, inflation depresses capitaland output and has a negligible effect on welfare.