Bootstrap Inference in Partially Identified Models Defined by Moment Inequalities: Coverage of the Identified Set

This paper introduces a novel bootstrap procedure to perform inference in a wide class of partially identified econometric models. We consider econometric models defined by finitely many weak moment inequalities, ² We can also admit models defined by moment equalities by combining pairs of weak moment inequalities.
which encompass many applications of economic interest. The objective of our inferential procedure is to cover the identified set with a prespecified probability. ³ We deal with the objective of covering each element of the identified set with a prespecified probability in Bugni (2010a).
We compare our bootstrap procedure, a competing asymptotic approximation, and subsampling procedures in terms of the rate at which they achieve the desired coverage level, also known as the error in the coverage probability. Under certain conditions, we show that our bootstrap procedure and the asymptotic approximation have the same order of error in the coverage probability, which is smaller than that obtained by using subsampling. This implies that inference based on our bootstrap and asymptotic approximation should eventually be more precise than inference based on subsampling. A Monte Carlo study confirms this finding in a small sample simulation.     

Inequality in voting power

This paper deals with the assessment of inequality in the distribution of voting power. Voting power is evaluated through a general concept of power measurement based on both the voting rule and the probability distribution over vote configurations. This general concept includes as particular cases the most usual power indices and other extensions of this traditional concept. Thus no particular power index is privileged in our approach. An inequality index over the class of all power profiles with a given number of voters generated by this general measure is then singled out by requiring reasonable properties. In order to compare profiles with different numbers of voters, two alternative principles are considered, which extend the said index consistently in two ways.Previous versions of this work were circulated under different titles. We gratefully acknowledge financial support from the Spanish Ministerio de Ciencia y Tecnología under the Ramón y Cajal programme and under projects PB96-0247 and BEC2000-0875; from the European Commission under the Training and Mobility of Researchers programme (contract FMRX - CT966-0055); and from the Instituto Valenciano de Investigaciones Económicas. We also thank two anonymous referees for their comments.2 October 2001     

Internationalisation and outsourcing of operations and product development in the fashion industry

This paper investigates the choices in terms of internationalisation and outsourcing of operations and product development activities, as well as collaboration practices used within and across organisations, in different segments of the European fashion industry. Based on multiple, in-depth case studies from Italy, Germany and the UK, the paper shows that fashion companies adopt different configurations of operations and product development, i.e. integrated, collaborative and virtual, ranging from local-integrated models to global-full outsourcing of operations and product development activities. For each configuration, different collaboration practices are in use. Product line positioning and quality, firm size, sales volumes and technical complexity of the products are the key drivers determining the configuration choices and the adoption of certain collaboration practices.     

The Impact of Privatization on the Earnings of Restructured Workers: Evidence From the Oil Industry

We study the long-term impact of job displacement from a big state owned enterprise as a result of its privatization in a developing country. Our results suggest large reductions in earnings, which persist throughout the years. However, we also find that the displaced worker’s post-displacement earnings are in line with competitive market wages, and unrelated to sector of employment or to tenure losses, indicating that the long-term reduction in earnings as a result of displacement because of privatization can be traced to the loss of wage rents. Our results indicate that job displacement in SOEs may have very large redistributive implications for the workers involved but that this loss does not necessarily reflect the loss of specific human capital associated to these jobs.

Fully Nonparametric Estimation of Scalar Diffusion Models

We propose a functional estimation procedure for homogeneous stochastic differential equations based on a discrete sample of observations and with minimal requirements on the data generating process. We show how to identify the drift and diffusion function in situations where one or the other function is considered a nuisance parameter. The asymptotic behavior of the estimators is examined as the observation frequency increases and as the time span lengthens. We prove almost sure consistency and weak convergence to mixtures of normal laws, where the mixing variates depend on the chronological local time of the underlying diffusion process, that is the random time spent by the process in the vicinity of a generic spatial point. The estimation method and asymptotic results apply to both stationary and nonstationary recurrent processes.     

A consistent and numerically efficient variable selection method for sparse Poisson regression with applications to learning and signal recovery

Statistics and Computing - We propose an adaptive $$\ell _1$$ -penalized estimator in the framework of Generalized Linear Models with identity-link and Poisson data, by taking advantage of a...     

Examining the Incidence and Clients’ Experiences of Single Session Therapy in Italy: A Feasibility Study

Single session therapy (SST) postulates that one session can be sufficient for a client to take charge of the process and work toward their own solutions. Research has been conducted worldwide corroborating SST assumptions with several mental health conditions, but not in Italy. For the first time in Italy, this paper aims to explore: (1) if the most frequent number of sessions in traditional psychotherapy (not SST) is one (Study 1); and (2) the satisfaction of clients who attend SST services and the number who consider one session sufficient to address their presenting problem (Study 2). In Study 1, the records of 476 voluntary clients referred to three different traditional (not SST) psychological services in the west-central region of Latium, Italy, were retrospectively screened, and the number of sessions attended by each client recorded. In Study 2, 85 consecutive clients who voluntarily asked for SST with seven mental health professionals across Italy received a link to an online ad hoc survey, 1–3 weeks after the consultation, evaluating their experience. Study 1 found that the most frequent number of traditional psychotherapeutic (not intentionally SST) sessions was one (124 out of 476 clients (26%). Study 2 found that 44 out of 85 clients (52%) considered one session to be enough, as they felt better or much better and chose not to attend further sessions. Of those who asked for a second session (41 clients), 33 clients (80.5%) indicated that the first session was not enough and 8 clients (19.5%) wanted to address a new problem. These results converge with previous international studies and provide encouragement for the use of SST in both private and public psychological services to address the demand for timely mental health services in Italy. Further research is needed to support the efficacy of SST and to evaluate its cost-effectiveness.     

Operationalizing De-commodification and De-familization Outcomes via the Relative Poverty Approach: An Application to Western European Countries

This article develops an approach with which to operationalise the outcomes of de-commodification and de-familisation processes. Since the de-commodification and de-familisation concepts share an emphasis on ‘a socially acceptable standard of living for individuals’ with the notion of relative poverty, the income-poverty indicator has been adopted to develop pertinent national rates. In particular, since de-commodification outcomes concern people with a socially acceptable standard of living independently of sale of their labour power, the national proportions of individuals with an equivalised disposable income above the poverty threshold who have stopped working have been accounted for. On the other hand, given that de-familisation outcomes regard individuals with a socially acceptable standard of living aside from family relationships, the national percentages of persons who actually live alone, or simulated as living alone, with an equivalised disposable income above the poverty threshold have been considered. Moreover, exploiting the equivalised disposable income computation, pertinent micro-simulations are developed to capture the role of the state and the family in de-commodification outcomes, and the contribution of the market and the state to de-familisation outcomes. On the basis of the European Union Statistics on Income and Living Conditions, an empirical application of this approach is then provided. Specifically, data for 16 European countries were used to compute the above-mentioned national rates. Furthermore, we checked whether our outcome figures exhibited any correspondence with the country-groups deriving from the classic welfare regime typologies or more in general with the measures resulting from the social policy structure.     

Kinematic analysis of post office employees' workstations

This study analyzed a post office clerk's tasks, comparing two workstation models. The clerk was facing the client in one, and seated at 45 degrees to the counter in the other. We analyzed the most frequent tasks and those presenting the most critical points: 1) payment of a postal order; 2) accepting a registered letter, breaking them down into subtasks. We used an optoelectronic system for kinematic analysis, and calculated the range of motion of the trunk and arms in the three spatial planes. The 45( position required less torsion of the trunk and head when using the printer, placed to the left of the employee. A larger worktop improved the workstation, leaving more room for equipment and allowing the worker to sit frontally to the monitor. However, this solution involved a shorter distance between the worker and the client with longer extension of the shoulder and elbow and less trunk flexion. These findings suggested a modification in the layout that shortens the distance between the worker and client.     

Distortions of Asymptotic Confidence Size in Locally Misspecified Moment Inequality Models

This paper studies the behavior, under local misspecification, of several confidence sets (CSs) commonly used in the literature on inference in moment (in)equality models. We propose the amount of asymptotic confidence size distortion as a criterion to choose among competing inference methods. This criterion is then applied to compare across test statistics and critical values employed in the construction of CSs. We find two important results under weak assumptions. First, we show that CSs based on subsampling and generalized moment selection (Andrews and Soares (2010)) suffer from the same degree of asymptotic confidence size distortion, despite the fact that asymptotically the latter can lead to CSs with strictly smaller expected volume under correct model specification. Second, we show that the asymptotic confidence size of CSs based on the quasi‐likelihood ratio test statistic can be an arbitrary small fraction of the asymptotic confidence size of CSs based on the modified method of moments test statistic.