Determination of recovery effort for a probabilistic recovery system under various inventory control policies

In this study we investigate the desired level of recovery under various inventory control policies when the success of recovery is probabilistic. All the used and returned items go into a recovery process that is modelled as a single stage operation. The recovery effort is represented by the expected time spent for it. The effect of increasing recovery effort on the success probability together with unit cost of the operation is included by assuming general forms of dependencies. Alternative to recovered items, demand is satisfied by brand-new items. Four inventory control policies that differ in timing of and information used in purchasing decision are proposed. The objective is to find the recovery level together with inventory control parameter that minimize the long-run average total cost. A numerical study covering a wide range of system parameters is carried out. Finally computational results are presented with their managerial implications.     

‘Democracy always comes first’: adolescents’ views on decision-making in everyday life and political democracy

Research shows adolescents to be positively oriented towards democracy, but little is known about what it actually means to them and what their views are on decision-making in both everyday situations and political democracy. To gain insight into these aspects of adolescents’ democratic views, we have interviewed 40 Dutch adolescents from second grade of different types of high school. Potential conflict between various democratic principles prevalent in everyday life situations was discussed and compared to how they view decision-making in political democracy. The results of our qualitative study showed that adolescents’ views on issues concerning collective decision-making in everyday situations are quite rich and reflect different models of democracy (majoritarian, consensual, and deliberative). Moreover, how adolescents deal with tensions between democratic principles in everyday life situations varies. While some adolescents combine several principles (for instance, majority rule as a last resort after trying to find broader consensus), other adolescents tend to strictly focus on only one of these principles. Adolescents’ views on political democracy, however, are rather limited and one-dimensional. Those adolescents who seemed to have a more explicit picture of political democracy often preferred a strict focus on majority rule, neglecting minority interests.     

Modeling the Adenoma and Serrated Pathway to Colorectal CAncer (ASCCA)

Several colorectal cancer (CRC) screening models have been developed describing the progression of adenomas to CRC. Currently, there is increasing evidence that serrated lesions can also develop into CRC. It is not clear whether screening tests have the same test characteristics for serrated lesions as for adenomas, but lower sensitivities have been suggested. Models that ignore this type of colorectal lesions may provide overly optimistic predictions of the screen‐induced reduction in CRC incidence. To address this issue, we have developed the Adenoma and Serrated pathway to Colorectal CAncer (ASCCA) model that includes the adenoma‐carcinoma pathway and the serrated pathway to CRC as well as characteristics of colorectal lesions. The model structure and the calibration procedure are described in detail. Calibration resulted in 19 parameter sets for the adenoma‐carcinoma pathway and 13 for the serrated pathway that match the age‐ and sex‐specific adenoma and serrated lesion prevalence in the COlonoscopy versus COlonography Screening (COCOS) trial, Dutch CRC incidence and mortality rates, and a number of other intermediate outcomes concerning characteristics of colorectal lesions. As an example, we simulated outcomes for a biennial fecal immunochemical test screening program and a hypothetical one‐time colonoscopy screening program. Inclusion of the serrated pathway influenced the predicted effectiveness of screening when serrated lesions are associated with lower screening test sensitivity or when they are not removed. To our knowledge, this is the first model that explicitly includes the serrated pathway and characteristics of colorectal lesions. It is suitable for the evaluation of the (cost)effectiveness of potential screening strategies for CRC.     

Poverty in People with Disabilities: Indicators from the Capability Approach

People with disability are particularly exposed to poor living conditions: on one hand they have more difficulties in getting an income cause to their inabilities, on the other hand conditions of poverty increase the risk of disability. However, little rigorous quantitative research has been undertaken to measure the real impact of disability on poverty. Methods based on monetary set (income and consumption) may not reflect the real possibility to convert resources into the fulfilment of personal goals. The capability approach, developed by A. K. Sen, offers a useful framework for the evaluation and assessment of individual well-being considering both monetary and non-monetary resources. The study describes a methodology, derived from the capability approach, to estimate the additional income needed for various types of household with and without disabled members to ensure the same satisfaction with economic resources. The method has been applied to the Italian contest, where 2.6 million people with disability live, and then the results are compared with the findings from an analogous study conducted in UK. The study reveals that disabled people in Italy need an income level two times higher to enjoy the same level of economic satisfaction, while in UK 50% of extra resource are sufficient. The findings suggests that traditional evaluations based on consumption lead to an underestimation of the needs of household containing disabled members. It follows that the financial benefits envisaged by actions planned by government through current instruments may not be completely effective.     

Bayesian estimation and case influence diagnostics for the zero-inflated negative binomial regression model

In recent years, there has been considerable interest in regression models based on zero-inflated distributions. These models are commonly encountered in many disciplines, such as medicine, public health, and environmental sciences, among others. The zero-inflated Poisson (ZIP) model has been typically considered for these types of problems. However, the ZIP model can fail if the non-zero counts are overdispersed in relation to the Poisson distribution, hence the zero-inflated negative binomial (ZINB) model may be more appropriate. In this paper, we present a Bayesian approach for fitting the ZINB regression model. This model considers that an observed zero may come from a point mass distribution at zero or from the negative binomial model. The likelihood function is utilized to compute not only some Bayesian model selection measures, but also to develop Bayesian case-deletion influence diagnostics based on q-divergence measures. The approach can be easily implemented using standard Bayesian software, such as WinBUGS. The performance of the proposed method is evaluated with a simulation study. Further, a real data set is analyzed, where we show that ZINB regression models seems to fit the data better than the Poisson counterpart.     

Dual class shares,board of directors’ effectiveness and firm’s market value: an empirical study

This study aims to identify whether a relationship exists between the controlling shareholders’ voting power and outside directors’ effectiveness in maximizing firms’ financial performance. We analyze a panel data with 3057 observations for the 2000–2012 period using a random effects model, logit and probit regressions, and the two-stage model of Heckman in the Brazilian stock market. Our findings show that firms whose controlling shareholders use dual class shares to leverage their voting power have less independence from the board and worse financial performance and market value. Further, the percentage of outside directors tends to be ineffective in increasing the firm’s value, and in changing the firm’s chief executive officer (CEO) when (1) the controlling shareholder’s voting power is leveraged, or (2) when the CEO assumes a position on the board of directors simultaneously. We interpreted that these results are in line with the arguments in favor of the existence of a new agency cost, which is related to the undue obedience of board members to authority, such as the largest controlling shareholder or the CEO in Brazilian listed firms.     

The price for information about probabilities and its relation with risk and ambiguity

In this article, ambiguity attitude is measured through the maximum price a decision maker is willing to pay to know the probability of an event. Two problems are examined in which the decision maker faces an act: in one case, buying information implies playing a lottery, while, in the other case, buying information gives also the option to avoid playing the lottery. In both decision settings, relying on the Choquet expected utility model, we study how the decision maker??s risk and ambiguity attitudes affect the reservation price for ambiguity resolution. These effects are analyzed for different levels of ambiguity of the act. Operating instructions for the elicitation of the reservation price for ambiguity resolution in an experimental setting are provided at the end of the article.