Modeling healthcare costs in simultaneous presence of asymmetry,heteroscedasticity and correlation

Highly skewed outcome distributions observed across clusters are common in medical research. The aim of this paper is to understand how regression models widely used for accommodating asymmetry fit clustered data under heteroscedasticity. In a simulation study, we provide evidence on the performance of the Gamma Generalized Linear Mixed Model (GLMM) and log-Linear Mixed-Effect (LME) model under a variety of data-generating mechanisms. Two case studies from health expenditures literature, the cost of strategies after myocardial infarction randomized clinical trial on the cost of strategies after myocardial infarction and the European Pressure Ulcer Advisory Panel hospital prevalence survey of pressure ulcers, are analyzed and discussed. According to simulation results, the log-LME model for a Gamma response can lead to estimations that are biased by as much as 10% of the true value, depending on the error variance. In the Gamma GLMM, the bias never exceeds 1%, regardless of the extent of heteroscedasticity, and the confidence intervals perform as nominally stated under most conditions. The Gamma GLMM with a log link seems to be more robust to both Gamma and log-normal generating mechanisms than the log-LME model.     

Kind of Black: The Musicians' Labour Market in Italy

It is estimated that only 5 per cent of musicians in Italy are regularly employed. In an attempt at understanding such a peculiar situation, we build a theoretical model of the musicians' labour market in which we embed the main institutional features of the Italian system. The presence of taxation encourages the formation of a black labour market for musicians and discourages talented agents from becoming full‐time musicians in all second‐best economies. In Italy both tendencies are particularly strong, and exacerbated by the peculiarities of the pension system for musicians. These inefficiencies might be corrected by a twofold policy: the reform of the pension system, highly desirable but unlikely to be politically feasible in the current Italian institutional setting, and the introduction of a sufficiently large unemployment benefit for musicians, step that has a general interest for any second‐best economy and not only for the case of the musicians' labour market, and that might instead be viable under certain circumstances.     

Survival Trees: An Alternative Non-Parametric Multivariate Technique for Life History Analysis

In this paper an extension of tree-structured methodology to cover censored survival analysis is discussed. Tree-based methods (also called recursive partitioning) provide a useful alternative to the classical survival data analysis techniques, such as the semi-parametric model of Cox, whenever the main purpose is defining groups of individuals, either with complete or censored life history, having different survival probability, based on the values of selected covariates. The essential feature of recursive partitioning is the construction of a decision rule in the form of a binary tree. Trees generally require fewer assumptions than classical methods and handle non standard and non linear data structures efficiently. Tree-growing methods make the processes of covariate selection and grouping of categories in event history models explicit. An example concerning the analysis of time to marriage of Italian women is presented.     

A new 'biased coin design' for the sequential allocation of two treatments

Summary.  Efron's biased coin design is a well-known randomization technique that helps to neutralize selection bias in sequential clinical trials for comparing treatments, while keeping the experiment fairly balanced. Extensions of the biased coin design have been proposed by several researchers who have focused mainly on the large sample properties of their designs. We modify Efron's procedure by introducing an adjustable biased coin design, which is more flexible than his. We compare it with other existing coin designs; in terms of balance and lack of predictability, its performance for small samples appears in many cases to be an improvement with respect to the other sequential randomized allocation procedures.     

A sociological economy of HIV/AIDS vaccine partnerships: case studies from Africa and India

Public–private partnerships (PPPs) are perhaps the key emergent theme in the delivery of what the socio-economic literature terms global public goods. In light of the problems relating to the distribution of health services and products in developing countries, partnerships between public and private institutions are often proposed as an innovative mechanism to reconnect and reorient supply and demand. In this area, the International Aids Vaccine Initiative (IAVI), which is driving the development of candidate HIV/AIDS vaccines through injections of capital into the research process, represents a significant case study. IAVI seeks to form partnerships between key public and private interests committing them to sharing the risks, costs and benefits of research into an effective and affordable vaccine against HIV. Our empirical work covers partnerships based in several countries including Kenya, Uganda, Rwanda and India. Our early findings highlight IAVI's ability as a learning institution as it adapts its institutional arrangements to various local contexts. An offshoot of this appears to be the building of real local capacity.     

“Good” corporate governance and the quality of internal auditing departments in Italian listed firms. An exploratory investigation in Italian listed firms

One of the most important issue relating to corporate governance reports refers to their ability to provide users with a complete set of information regarding the effective ability of an entity to achieve oversight objectives by the compliance to corporate governance practices required by a specific law or industry code. In addition, other features, such as the quality of the internal auditing function or the sensitivity of top management to issues relating to corporate internal controls and risk management, can also be taken into account when formulating a judgment on the quality of corporate governance practices. Is there an association between the compliance to codes and internal controls effectiveness? We propose to assess the quality of corporate governance through a proxy that considers several characteristics of internal audit departments and combines them to determine an Internal Audit Departments global quality index—IAD Index. To define IAD global quality we consider the effectiveness of an internal audit function analysing its operational aspects. The IAD Index is based on several signalling elements that previous literature assumed as proxies for quality of IADs which are grouped into four pillars: a formal quality index; a static quality index; an activity-related quality index; and a performance-linked quality index. We then test the IAD index on a sample of Italian listed firms and conclude that there are significant associations (positive and negative) between the degree of compliance to some corporate governance regulations for listed firms and the IAD Index for the sample being considered.     

Dynamic capabilities and high-tech entrepreneurial ventures’ performance in the aftermath of an environmental jolt

This paper contributes to studies on dynamic capabilities (DCs) by showing that a neglected environmental contingency – i.e. the occurrence of a jolt – shapes the DCs–performance relationship. We focus on high-tech entrepreneurial ventures because these are the firms that jolts affect most; in so doing, we also advance the understanding of DCs in the entrepreneurship field. We argue that, in the aftermath of an environmental jolt, the high-tech entrepreneurial ventures that use internationalization and new product development capabilities to modify their resource configuration and regain environmental fit enjoy better performance. Econometric estimates on a sample of 340 Italian high-tech entrepreneurial ventures confronting the consequences of the global economic crisis that began in 2008 confirm that separately using these two DCs has a positive performance effect. This effect is stronger for relatively smaller ventures. Interestingly, despite synergies should arise from the combined use of the two DCs, we do not detect any superadditive effects.     

Going concern modifications and related disclosures in the Italian stock market: do regulatory improvements help investors in capturing financial distress?

Journal of Management and Governance - This paper investigates the investor reaction to audit reports containing a going concern modification (GCM) in the Italian market following new amendments...