Matching on the Estimated Propensity Score

Propensity score matching estimators (Rosenbaum and Rubin (1983)) are widely used in evaluation research to estimate average treatment effects. In this article, we derive the large sample distribution of propensity score matching estimators. Our derivations take into account that the propensity score is itself estimated in a first step, prior to matching. We prove that first step estimation of the propensity score affects the large sample distribution of propensity score matching estimators, and derive adjustments to the large sample variances of propensity score matching estimators of the average treatment effect (ATE) and the average treatment effect on the treated (ATET). The adjustment for the ATE estimator is negative (or zero in some special cases), implying that matching on the estimated propensity score is more efficient than matching on the true propensity score in large samples. However, for the ATET estimator, the sign of the adjustment term depends on the data generating process, and ignoring the estimation error in the propensity score may lead to confidence intervals that are either too large or too small.     

Semiparametric Estimates of Monetary Policy Effects: String Theory Revisited

We develop flexible semiparametric time series methods for the estimation of the causal effect of monetary policy on macroeconomic aggregates. Our estimator captures the average causal response to discrete policy interventions in a macrodynamic setting, without the need for assumptions about the process generating macroeconomic outcomes. The proposed estimation strategy, based on propensity score weighting, easily accommodates asymmetric and nonlinear responses. Using this estimator, we show that monetary tightening has clear effects on the yield curve and on economic activity. Monetary accommodation, however, appears to generate less pronounced responses from both. Estimates for recent financial crisis years display a similarly dampened response to monetary accommodation.     

A survival analysis of the last great European plagues: The case of Nonantola (Northern Italy) in 1630

This paper develops the first survival analysis of a large-scale mortality crisis caused by plague. For the time-to-event analyses we used the Cox proportional hazards regression model. Our case study is the town of Nonantola during the 1630 plague, which was probably the worst to affect Italy since the Black Death. Individual risk of death did not depend on sex, grew with age (peaking at ages 40–60 and then declining), was not affected by socio-economic status, and was positively associated with household size. We discuss these findings in light of the historical–demographic and palaeo-demographic literature on medieval and early modern plagues. Our results are compatible with the debated idea that ancient plague was able to spread directly from human to human. Our methods could be replicated in other studies of European plagues to nuance and integrate the findings of recent palaeo-biological and palaeo-demographic research on plague.     

The connectivity of ethnic displays: new codes for identity in northern Laos

In Laos, cultural festivals and other forms of ethnic display communicate locality and ethnicity to external agencies, in particular the nation state. This article documents strategies of identity-making in a small festival that was staged spontaneously in a Rmeet (Lamet) village. The chosen representations were conventional: dance, music, clothing. The Rmeet thereby employed a festival code used by numerous minorities worldwide. But these recently invented traditions are continuous with earlier representations that addressed various categories of strangers, including historic states and non-state groups. What has changed is the connectivity of the representations. Dance or costume used to represent external relationships in the past, but have been recoded for present use. Moreover, Rmeet have appropriated a New Year’s festival invented by the neighboring Khmu. Thus, ethnic displays appear as the most recent way of communicating difference in a code that connects them with the state, neighboring ethnicities, and a global language of locality.     

Trunk stabilization with sling training in osteoporosis patients—a randomized clinical trial

Fractures due to osteoporosis are one of the principal causes of functional limitations, chronic pain, and greater morbidity in advanced age. In addition to bone risk factors for osteoporotic fractures include extraosseous causes such as falls or reduced neuromuscular capacity. Muscle and coordination exercises enhance the patients’ abilities in daily life and prevent falls. In view of recent conclusions drawn from competitive sports, which stress the significance of the muscles of the trunk in respect of reducing back pain and optimizing posture, we used sling exercises to determine whether osteoporosis patients benefit from it and whether it is more advantageous than traditional physiotherapy. Fifty patients were randomized into two groups. Group A received traditional physiotherapy, while group B was given sling exercises, in each case twice a week for a period of 3 months. The results of treatment (pre-post) were analyzed in terms of pain levels, mobility, trunk strength, and the shape of the back. After a further 3 months with no specific exercise treatment, we retested all patients in order to draw conclusions about the long-term effects of the two types of exercise. Forty-four patients (88 %) completed the study. Patients were assigned to small groups (a maximum of five patients in each group) and, thus, received individual attention and motivation. Positive training effects were achieved in both groups. Significantly better results as regards improvement of mobility and reduction of falls were registered in the sling exercise group.     

My parents taught Me. Evidence on the family transmission of values

The paper uses questions included in the 2010 wave of the Bank of Italy’s Survey on Household Income and Wealth to investigate the role of family transmission of values. It presents three main empirical findings. First, the paper shows that a number of attitudes (generalized and personalized trusting behaviour, risk and time preferences) and outcomes (female labour force participation, fertility, entrepreneurship, productivity) are associated with the values received. Second, it documents that values received from parents are correlated with the values transmitted to descendants. Third, by using respondent moving patterns, the paper highlights that values received are slowly changing even after a discontinuity in the reference environment. Comparisons between first- and second-generation movers suggest that what matters for breaking the family chains are the formative years, when young people somehow strike a balance between the values transmitted by their parents and what they experience in the (possibly different) environment where they grow up.     

Workers’ Perception of Chemical Risks: A Focus Group Study

Workers’ perceptions with respect to health and safety at work are rarely taken into account when considering the development of prevention programs. The aim of this study was to explore workers’ perceptions of chemical risks at the workplace, in order to investigate the prerequisites for a workplace health program. A qualitative study was conducted involving seven focus groups of 5–10 participants (blue‐collar workers) each. All groups were homogeneous in terms of sex, work status, language, and company membership. Results showed that several factors have an important influence on workers’ perception of chemical risks. Workers assess risks by means of both sensory and empirical diagnosis and are concerned about the long‐term health consequences. They perceive the threat of chemical risks as high. Despite this, they are resigned to accepting the risks. Existing formal sources of information are rarely consulted because they are judged to be difficult to understand and not user friendly. Instead, workers tend to obtain information from informal sources. Communication problems with and lack of trust in prevention advisers and hierarchy are frequently mentioned. Workers feel that their specific knowledge of their working conditions and their proposals for practical, cost‐effective solutions to improve health and safety at the workplace are insufficiently taken into account. The use of focus groups yielded a useful insight into workers’ perceptions of chemical risks. Our findings suggest that training programs for prevention advisers should include topics such as understanding of workers’ perceptions, usefulness of a participatory approach, and communication and education skills.     

Liquidity and Trading Dynamics

In this paper, we build a model where the presence of liquidity constraints tends to magnify the economy's response to aggregate shocks. We consider a decentralized model of trade, where agents may use money or credit to buy goods. When agents do not have access to credit and the real value of money balances is low, agents are more likely to be liquidity constrained. This makes them more concerned about their short‐term earning prospects when making their consumption decisions and about their short‐term spending opportunities when making their production decisions. This generates a coordination element in spending and production which leads to greater aggregate volatility and greater comovement across producers.     

The Impact of Information Sharing on Supply Chain Performance under Asymmetric Information

The use of screening contracts is a common approach to solve supply chain coordination problems under asymmetric information. One main assumption in this context is that managers without specific incentives would rather use their private information strategically than reveal it truthfully. This harms supply chain performance. This study investigates the impact of information sharing in a principal‐agent setting that is typical for many supply chain transactions. We conduct a laboratory experiment to test whether information sharing has an influence on supply chain coordination. We find that information sharing within the supply chain has two positive effects. First, information sharing reduces the inefficiencies resulting from information deficits if there is a certain amount of trust in the supply chain. Second, communication can limit out‐of‐equilibrium behavior with a small impact on the firm's own payoff, but a large impact on the supply chain partner. Furthermore, we find that both effects are amplified when communication takes place in an environment that allows the less informed supply chain party to punish or to reward the better informed party. Although our extended mechanisms substantially enhance the poor performance of the theoretically optimal coordination contract menu, we find no mechanism that implements supply chain performance superior to the theoretically predicted second‐best level.     

A psychometric evaluation of a Dutch version of the Job Content Questionnaire and of a short direct questioning procedure

Using the demand-control-support perspective on job stress, a Dutch translation of an adapted version of the Job Content Questionnaire (AJCQ) was administered to a large population ( N = 3638) of Flemish workers in a variety of jobs, together with the General Health Questionnaire, and a negative affectivity scale. Overall, the AJCQ was shown to be a solid measurement instrument as indicated by several estimated reliability indices and validity of the subscales. A factor analysis largely reproduced the a priori structure of the AJCQ. A short 10-item direct questioning procedure was constructed to measure the 10 subscales of the AJCQ and the results of this procedure were compared with the AJCQ in a subsample ( N = 660). The correlations with six criterion variables showed that single questions were equally predictive than the much longer version of the AJCQ.