Chapter Post-stratification as a tool for enhancing the predictive power of classification methods

It is well known that, in classification problems, the predictive capacity of any decision-making model decreases rapidly with increasing asymmetry of the target variable (Sonquist et al., 1973; Fielding 1977). In particular, in segmentation analysis with a categorical target variable, very poor improvements of purity are obtained when the least represented modality counts less than 1/4 of the cases of the most represented modality. The same problem arises with other (theoretically more exhaustive) techniques such as Artificial Neural Networks. Actually, the optimal situation for classification analyses is the maximum uncertainty, that is, equidistribution of the target variable. Some classification techniques are more robust, by using, for example, the less sensitive logit transformation of the target variable (Fabbris & Martini 2002); however, also the logit transformation is strongly affected by the distributive asymmetry of the target variable. In this paper, starting from the results of a direct survey in which the target (binary) variable was extremely asymmetrical (10% vs. 90%, or greater asymmetry), we noted that also the logit model with the most significant parameters had very reduced fitting measures and almost zero predictive power. To solve this predictive issue, we tested post-stratification techniques, artificially symmetrizing a training sample. In this way, a substantially increase of fitting and predictive capacity was achieved, both in the symmetrized sample and, above all, in the original sample. In conclusion of the paper, an application of the same technique to a dataset of very different nature and size is described, demonstrating that the method is stable even in the case of analysis executed with all data of a population

Endothelial and Metabolic Function Interactions in Overweight/Obese Children.

AIM: Although the underlined mechanisms are still unknown, metabolic/coagulation alterations related to childhood obesity can induce vascular impairments. The aim of this study was to investigate the relationship between metabolic/coagulation parameters and endothelial function/vascular morphology in overweight/obese children. METHODS: Thirty-five obese/overweight children (22 pre-pubertal, mean age: 9.52±3.35 years) were enrolled. Body mass index (BMI), homeostasis model assessment index (HOMAIR), metabolic and coagulation parameters, [adiponectin, fibrinogen, high molecular weight adiponectin (HMW), endothelin-1, and vonWillebrand factor antigen] ultrasound early markers of atherosclerosis [flow-mediated dilatation (FMD), common carotid intima-media thickness (C-IMT), and anteroposterior diameter of infra-renal abdominal aorta (APAO)] were assessed. RESULTS: APAO was related to anthropometric (age: r=0.520, p=0.001; height: r=0.679, p＜0.001; weight: r=0.548, p=0.001; BMI: r=0.607, p＜0.001; SBP: r=0.377, p=0.026) and metabolic (HOMAIR: r=0.357, p=0.035; HMW: r=－0.355, p=0.036) parameters. Age, height, and systolic blood pressure were positively related to increased C-IMT (r=0.352, p=0.038; r=0.356, p=0.036; r=0.346, p=0.042, respectively). FMD was not related to any clinical and biochemical characteristics of the pediatric population. Age, HOMAIR, fasting glucose levels, and HMW were independent predictors for APAO increase. Each unit decrease in HMW concentrations (1 μg/ml) induced a 0.065 mm increase in APAO. CONCLUSION: High molecular weight adiponectin is related to cardiovascular risk in overweight/obese children

Degenze ospedaliere per malattie cardiovascolari in Puglia.

Nel presente lavoro è stata effettuata, usando tecniche classiche di esplorazione statistica uni/multivariata, una analisi di durata dei ricoveri per patologie cardiovascolari, aggregate per gruppo clinico di diagnosi (CCS, Clinical Classification Software), valutando l’influenza delle varie patologie e di altri fattori prognostici caratterizzanti ogni paziente ricoverato (età, sesso, provincia di residenza e altro ancora) sulla durata della degenza. La tecnica utilizzata è ben nota in ambito epidemiologico, ma è qui gestita in modo alternativo

Dimensioni latenti dell’attitudine al gioco di fortuna in età adolescenziale

Nel corso degli ultimi anni il gioco d’azzardo è diventato, anche in Italia, un'attività di massa di vastissime proporzioni economiche e sociali. Infatti, in alcuni casi la pratica del gioco d'azzardo può degenerare in una situazione di dipendenza psicologica che porta tendenzialmente alla rovina economica del giocatore. In questa ricerca, si è affrontato il fenomeno "alla base", nelle scuole, cercando di coinvolgere gli alunni delle scuole secondarie di II grado di Bar

Multivariate data analysis techniques for healthcare organizational efficiency improvement

The main way to reduce costs ensuring good healthcare standards and improving the benefit-cost ratio, in Italy as well as in other countries, is connected to organizational choices: by example, the organizational pertinence in hospitalization typology (“ordinary admission” vs “day hospital/day surgery”). This paper aims to investigate such type of efficiency in healthcare facilities by using multivariate methods of data mining, precisely logit regression, segmentation analysis, and neural networks, in order to assess the organizational appropriateness, evaluating the incidence of the day hospital and day surgery procedures and analysing their relevance in the health system, as well as their pertinence level. Starting by a set of hospital administrative data (deriving from Hospital Discharge Datasheet provided by all Apulian healthcare facilities), this study provides interesting results about the decisional mechanism of the Healthcare management, as well as the ranking of organizational efficiency in the health Apulian network. Further analyses could clarify how (and how much) these results can be extended to other territorial systems

A health case for e-government

Nowadays, e-government is a key theme, focused on a set of digital public utilities offered to citizens in order to reduce administrative burdens with the use of information and communication technologies. The proposed work aims to propose a procedure for simplification of classification of medical and health data in order to efficiently support e-government in healthcare, having a large amount of data (more than 800.000 hospitalizations), provided by healthcare organizations located all over the Apulian territory in 2014. These data must be transformed into information to be managed in an optimal way for the Puglia region. By using different techniques of statistical data exploration and multivariate data analysis, we here focus on a descriptive epidemiological analysis, based on duration of hospitalization, aggregated by clinical diagnosis group (CCS, Clinical Classification Software), distinguishing between multi pathologies within the CCS and between CCS. As reference variable we use not only diagnosis item, but also some variables that characterize each hospitalized patient, such as age, sex, province of residence, the province of birth, month of hospitalization etc

The quality of public transport services: a statistical analysis

The purpose of this study is to investigate what kind of observable and non-observable factors can influence passenger satisfaction on the quality of public transport services in a local context, on the basis of a sample survey. Of course, these results can be used by the transport company in order to modify its business strategies and to improve its business performance and competitive advantage. In the first step, relationships among the intangible dimensions such as quality, satisfaction and loyalty are defined using suitable statistical measuring techniques (Factor Analysis on the results of a Categorical Principal Component Analysis). Successively, multivariate methods are used in order to explore the characteristics of the customers and their weight on the quality perception. The final result of this analysis is a Structural Equation Model, assumed as representative of the customer’s behaviour towards quality in public transport, useful to understand the challenges of the strategic orientation and those of the marketing management

Validity and efficacy of crime perception by families as a crime indicator: A study on Italian statistics.

Despite that official data about crime in Italy (yearly provided by Authorities) describe a downward trend, the population’s perception on this issue seems to be much less optimistic, outlining a country where the citizens feel less and less safe and less confident in the protection offered by the judicial system. In the last years such perception induced many modifications in social behaviours (also in terms of electoral outcomes), but its relationship with the actual crime dynamics is unclear, maybe only due to information bias. Furtherly, a commonly held view is that the justice system in Italy is busy, chaotic and rather poorly administered. In this communication, several statistical methodologies are used in order to evaluate whether and how the objective dynamics of the main crimes can influence the subjective perception of safety and legality; the same analysis is carried out about justice procedures on crimes (described as suggested in Cook and Johnson 1981, Wilodhorn and Wilodhorn 1977). In this way, perhaps some ameliorative intervention could be identified, including legislative measures and/or administrative processes enhancements (Sciacca, 2007). At the same time, this analysis provides an interesting frame of the cross-dynamics among the main crimes and the crime justice indicators, and tries to determine whether the subjective perception of safety and legality (considered as a cross outcome of crime dynamics and justice results) can be used as a proxy to evaluate the effectiveness of justice

Assisted suicide in the care of mentally ill patients: The Lucio Magri's case

A year after Mario Monicelli's suicide, the death of another famous person in Italy, Lucio Magri, reawakened the Italian debate on social, ethical and juridical issues in end-of-life decisions. Unlike Monicelli, Lucio Magri decided to end his own life in Switzerland with the help of a physician because his mental illness rendered his life unbearable. Both Monicelli and Magri suffered from a severe depression. The authors analyze the ethical issues regarding the right to die for mentally ill patients and neurological disabled patients, discussing the decision-making autonomy in persons suffering from severe depression. The role of the psychiatry in the management of end-of-life decision requests is considered along with pros and cons of suicide prevention and rationale suicide. © 2013 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved