Pitfalls of Normal-Gamma Stochastic Frontier Models

Although conceptually pleasing, normal-gamma frontier models lead to difficult estimation problems. It is shown here that unless the sample size reaches several thousands of observations the shape parameter of the gamma density is hard to estimate, and that this carries over to estimates of the stochastic frontier, the individual inefficiencies, and the allocation of the overall variance to the stochastic frontier and to the inefficiencies.     

A nonparametric analysis of multi-product oligopolies

We develop revealed preference tests for models of multi-product oligopoly, building on the work in Carvajal et al. (Econometrica 81(6):2351–2379, 2013). We analyze a Cournot model with multiple goods and show that it has testable restrictions when at least one good is produced by two or more firms. We also develop a revealed preference test for Bertrand oligopoly in a setting where each firm produces a single differentiated good, and these goods are potentially substitutes for each other. Our tests require qualitative assumptions on the shape of the demand curves and (in the Bertrand case) their evolution across observations, but they do not rely on the estimation of market demand.     

Public or Private Sector Wage Leadership? An International Perspective*

Whether a government acts as a wage leader, placing pressure on private‐sector wages (more open to competition), or whether it plays a passive role and merely follows wage negotiations in the private sector, there are important implications for macroeconomic development, particularly in small open economies and/or countries that are members of a monetary union, such as those of the European Monetary Union. With the notable exception of the case of Sweden, opinion on this issue is still divided. In this paper, we look at public‐ and private‐sector wage interactions from an international perspective (18 OECD countries). We focus on the causal two‐way relationship between public and private wage setting, confirming that the private sector, on the whole, appears to have a stronger influence on the public sector, rather than vice versa. However, we also find evidence of feedback effects from public wage setting, which affect private‐sector wages in a number of countries. When the private sector takes the lead on wages, there are few feedback effects from the public sector, while public wage leadership is typically accompanied by private‐sector feedback effects.     

Political objectives and privatization decisions

In early Romanian privatization a group of firms was explicitly banned from privatization. We use this institutional feature to test which factors contributed to the selection of firms for long‐term state ownership, and find that politicians sheltered from privatization large and inefficient firms which paid low wages and had high overdue payments. These results are consistent with minimization of employment losses, even if efficiency enhancement of privatization had to be sacrificed. We conjecture that the unfavourable economic conditions bringing large employment losses motivated Romanian politicians to fear the possible negative employment effects of privatization.     

Nowcasting the French index of industrial production: A comparison from bridge and factor models

Governments and central banks need to have an accurate and timely assessment of indicators for the current month, as this is essential for providing a reliable and early analysis of the current economic situation. The index of industrial production (IIP) is probably the most important and widely analyzed monthly indicator, given the relevance of the manufacturing activity as a driver of the whole business cycle. This paper presents a series of models conceived to forecast the current French monthly IIP, based on regression models and dynamic factor models. The combination of these two approaches allows selecting economically relevant explanatory variables among a large data set. In addition, a rolling forecast study is carried out to assess the forecasting performance of the estimated models, using predictive ability and model confidence set tests. This latter allows getting several models displaying equivalent forecasting performance and therefore gives robustness to the forecasting exercise rather than to base the forecasting analysis only on one model.     

Romanians,Hungarians and their wages,in transition,in Romania

Legally binding treaties or memorandums have been used over time to regulate the issue of national borders of many European countries. As a result, relatively large groups of people have become ethnic minorities in other countries. They may conserve their ethnic identities, and therefore their children may accumulate ethnic human capital (e.g., language, culture, and religion) in addition to the general human capital of the country. Therefore, they can get access to an appropriate occupation linked by tradition or other factors to their ethnic group. This paper uses estimates from a selection model with an endogenous switch among three broad types of occupational groups to analyze the composition of the wage gap between Romanians and ethnic Hungarians in Romania before and during the transition from a planned to a market economy. The results suggest that the institutional settings of the controlled economy allowed Romanians to work in occupations that gave them the best returns, while the changes during the transition years allowed ethnic Hungarians to work in occupations that gave them the best returns.     

Asymmetry, realised volatility and stock return risk estimates

In this paper we estimate minimum capital risk requirements for short and long positions with three investment horizons, using the traditional GARCH model and two other GARCH-type models that incorporate the possibility of asymmetric responses of volatility to price changes. We also address the problem of the extremely high estimated persistence of the GARCH model to generate observed volatility patterns by including realised volatility as an explanatory variable into the model??s variance equation. The results suggest that the inclusion of realised volatility improves the GARCH forecastability as well as its ability to calculate accurate minimum capital risk requirements and makes it quite competitive when compared with asymmetric conditional heteroscedastic models such as the GJR and the EGARCH.     

Economic modelling of costs associated with outcomes reported for type 2 diabetes mellitus (T2DM) patients in the CANVAS and EMPA-REG cardiovascular outcomes trials

Aims: To model direct medical costs associated with reductions in cardiovascular disease (CVD) events in T2DM patients reported in the CANVAS and EMPA-REG trials, which assessed the cardiovascular safety of canagliflozin and empagliflozin, respectively.

Materials and methods: Costs were modeled from a US managed care organization (MCO) perspective for the CVD outcomes included in both trials: three-point major adverse cardiovascular event (MACE) and its components (cardiovascular-related death, nonfatal myocardial infarction, nonfatal stroke), as well as heart failure requiring hospitalization. The rate of CVD events averted (difference between study drug and placebo) was projected to the portion of an MCO T2DM population matching the respective trial’s inclusion criteria. A targeted literature search for paid amounts directly associated with each CVD event provided the unit costs, which were applied to the projected number of events averted, to calculate costs avoided per member per year (PMPY). One-way sensitivity analyses were performed on events averted, unit costs, and percentages of trial-applicable patients.

Results: Based on three-point MACE events averted, costs avoided PMPY of $6.17 (range: $1.27–$10.94) for CANVAS and $2.75 ($0.19–$4.83) for EMPA-REG were estimated. Costs avoided for individual components of MACE ranged from $0.77 to $3.84 PMPY for CANVAS and from -$0.97 (additional costs) to $1.54 for EMPA-REG. PMPY costs avoided for heart failure were $2.72 for CANVAS and $1.32 for EMPA-REG.

Limitations and conclusions: Models assumed independent, non-recurrent outcomes and were restricted to medical costs directly associated with the trial-reported events. The reductions in CVD events in T2DM patients reported for both CANVAS and EMPA-REG project to a positive cost avoidance for these events in an MCO population. The analysis did not include an assessment of the impact on total cost, as the costs associated with adverse events, drug utilization or other clinical outcomes were not examined.     

Healthcare costs of stroke and major bleeding in patients with atrial fibrillation treated with non-vitamin K antagonist oral anticoagulants

Objective: To assess long-term healthcare costs related to ischemic stroke and systemic embolism (stroke/SE) and major bleeding (MB) events in patients with non-valvular atrial fibrillation (NVAF) treated with non-vitamin K antagonist oral anticoagulants (NOACs).

Materials and methods: Optum’s Clinformatics Data Mart database from 1/2009–12/2016 was analyzed. Adult patients with ≥1 stroke/SE hospitalization (index date) were matched 1:1 to patients without stroke/SE (random index date), based on propensity scores. Patients with an MB event were matched to patients without MB. All patients had an NOAC dispensing overlapping index date, ≥12?months of eligibility pre-index date, and ≥1 NVAF diagnosis. The observation period spanned from the index date until the earliest date of death, switch to warfarin, end of insurance coverage, or end of data availability. Mean costs were evaluated: (1) per-patient-per-year (PPPY) and (2) at 1, 2, 3, and 4?years using Lin's method.

Results: The cost differences were, respectively, $48,807 and $28,298 PPPY for NOAC users with stroke/SE (n?=?1,340) and those with MB (n?=?3,774) events compared to controls. Cost differences of patients with vs without stroke/SE were $49,876, $51,627, $57,822, and $60,691 at 1, 2, 3, and 4?years post-index, respectively (p?p?Limitations: Limitations include unobserved confounders, coding and/or billing inaccuracies, limited sample sizes over longer follow-up, and the under-reporting of mortality for deaths occurring after 2011.

Conclusions: The incremental healthcare costs incurred by patients with vs without stroke/SE was nearly twice as high as those of patients with vs without MB. Moreover, each additional year up to 4?years after the first event was associated with an incremental cost for patients with a stroke/SE or MB event compared to those without an event.