cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
A two-factor model of the term structure with optimal filtering behaviour
Creators: name: Fornari, F.
name: Mele, A.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: The rates of return of financial variables observed at high frequency are not normally distributed, mainly because of positive excess kurtosis; thus, most of the models developed in financial economics need be modified to take into account such characteristics of the data. On this respect GARCH models provide an appropriate modelling framework. Building on the convergence of an AR(1)-GARCH(1,1) model to a bivariate Ito process, we present a two-factor model for the term structure of interest rates and derive the closed-form solution for the price of zero-coupon bonds. The estimation of such a model can be carried out by means of an AR(1)-GARCH(1,1) scheme, which represents its discrete-time version.
description: Statistica; Vol 54, No 3 (1994)
A note on the equivalence between certain equivalent and least expected penalization criteria
Creators: name: Capotorti, A.
name: Di Bacco, M.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: In this paper we face the problem of the uniqueness of the quadratic penalty func-tion. We show an elementary case where the equivalence between certain equivalent and least expected penalization criteria reached by means of a wider class than the quadratic one. The uniqueness is obtained only imposing a symmetry condition.
description: Statistica; Vol 56, No 2 (1996)
The italian term structure of interest rates and the currency devaluation of september 1992: a factor-arch analysis
Creators: name: Pellinzoni, L.
name: Weber, G.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: This paper estimates the Italian term structure of the interest rates. The focus of the paper is to explain the term premium by the identification of the observable factors which influence this premium. Using a Factor-Arch model it is found that two factors determine the term premium. One of the factors is national and the other one is international.
description: Statistica; Vol 54, No 3 (1994)
A nonlinear model for the conditional expectations of asset returns
Creators: name: Paruolo, P.
name: Pillati, M.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: Several financial theories suggest a factor structure for the conditional expectations of asset returns. The number of factors can often be used to discriminate among competing theories. In this paper we generalize the approach of  Costa et al. (1992) employing a neural network architecture to model the conditional expectation of asset returns. The identification problem of such models is discussed, and likelihood inference developed. An application illustrates the approach.
description: Statistica; Vol 54, No 3 (1994)
A class of unbiased ratio estimators in two-phase sampling
Creators: name: Singh, H. P.
name: Biradar, R. S.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: A class of unbiased ratio-type estimators in two (double) phases sampling has been constructed. It has been shown that Sukhatme's (1962) estimator is a particular member of the proposed class. Variance expression of the proposed class has been derived and optimum estimator in the class is identified. An empirical study is carried out to illustrate the performances of constructed estimator over various other estimators. Further, the cost aspect has also been considered.
description: Statistica; Vol 54, No 3 (1994)
Moments and other expected values for matrix variate elliptically contoured distribution,
Creators: name: Gupta, A. K.
name: Varga, T.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: In this paper, moments and other expected values of functions of matrix variate elliptically contoured distribution are studied. A relationship is pointed out between the expected values for the normal case and the general elliptical case. Expected values of concrete functions are derived. An example is given when the underlying distribution is Student's t-distribution.
description: Statistica; Vol 54, No 3 (1994)
Determination of optimum strata boundaries for scrambled randomized response
Creators: name: Mahajan, P. K.
name: Gupta, J. P.
name: Singh, R.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: The paper considers the problem of finding optimum strata boundaries (OSB) when the samples from different strata are selected with simple random sampling and with replacement (SRSWR) and the data are collected by scrambled randomized response technique on the sensitive character. The paper proposes a rule for finding approximately optimum strata boundaries (AOSB).
description: Statistica; Vol 54, No 3 (1994)
On estimation of mean/total of stigmatized quantitative variable
Creators: name: Singh, S.
name: Mangat, N. S.
name: Singh, R.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: This paper presents an improvement of randomized response model considered by Greenberg et al. (1971) for estimation of mean of sensitive variables. The proposed modification is for quantitative characters analogous to Mangat and Singh's (1990). The present modification yields an estimator which is always more precise than the one due to Greenberg et al. (1971).
description: Statistica; Vol 54, No 3 (1994)
Concept and basic framework prototype for a flexible and intervention-independent situation recognition system in the OR
Creators: name: Junger, Denise
name: Hirt, Bernhard
name: Burgert, Oliver
Publisher: name: Taylor & Francis
Year: 2021
Subjects: subject: Space Science
subject: Medicine
subject: 69999 Biological Sciences not elsewhere classified
subject: FOS: Biological sciences
subject: 80699 Information Systems not elsewhere classified
subject: FOS: Computer and information sciences
subject: Science Policy

description: Context-aware systems to support actors in the operating room depending on the status of the intervention require knowledge about the current situation in the intra-operative area. In literature, solutions to achieve situation awareness already exist for specific use cases, but applicability and transferability to other conditions are less addressed. It is assumed that a unified solution that can be adapted to different processes and sensors would allow for greater flexibility, applicability, and thus transferability to different applications. To enable a flexible and intervention-independent system, this work proposes a concept for an adaptable situation recognition system. The system consists of four layers with several modular components for different functionalities. The feasibility is demonstrated via prototypical implementation and functional evaluation of a first basic framework prototype. Further development goal is the stepwise extension of the prototype.
Surgical instrument grounding for robot-assisted interventions
Creators: name: González, Cristina
name: Bravo-Sanchéz, Laura
name: Arbeláez, Pablo
Publisher: name: Taylor & Francis
Year: 2021
Subjects: subject: Space Science
subject: Medicine
subject: Neuroscience
subject: Sociology
subject: FOS: Sociology
subject: 69999 Biological Sciences not elsewhere classified
subject: FOS: Biological sciences
subject: 80699 Information Systems not elsewhere classified
subject: FOS: Computer and information sciences
subject: Science Policy

description: We present the first experimental framework for segmenting instruments in surgical scenes guided by natural language descriptions. Previous approaches rely exclusively on visual cues, thus ignoring the fine-grained nature of the problem. We exploit the rich domain knowledge of function by introducing structured descriptions. Our method, the Language-Guided Instrument (LGI) Segmentation network, merges three levels of information to compute the probability of an object candidate belonging to each surgical instrument category: context information (the image’s features), local information (the candidate’s features) and language information (a sentence per class), in which we include the differentiating details of each instrument type. We perform a comprehensive experimental evaluation over the standard benchmarks for the task and we show that LGI enhances the performance of different backbone instance segmentation methods, obtaining a significant improvement over the state-of-the-art. To the best of our knowledge, we propose the first experimental framework for jointly applying vision and language to a high-impact global healthcare problem.
Woman roles between family and employment: empirical evidence from individual data
Creators: name: Egidi, V.
name: Sabbadini, L. L.
name: Zaccarin, S.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: Status of women is generally recognized as a key variable in the analysis of demographic and social behaviour. Women's status is a multidimensional concept that rises from the complex interactions of different factors. In this paper, the links between women individual characteristics and roles that women played are analysed by the means of a sequence of multivariate techniques. Data are taken from the Italian Multipurpose Survey and the roles of worker, wife and mother are considered.
description: Statistica; Vol 54, No 4 (1994)
Family structure and income: a first analysis on a cross-section data
Creators: name: Angeli, Aurora
name: Cocchi, Daniela
name: Pasquini, Lucia
name: Samoggia, Alessandra
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: In the paper the hypothesis of differences in household incomes depending on the sex of the householder is investigated. The data come from the 1991 Bank of Italy Survey on Household Income, which is the only source available to such a purpose. A multiple regression model has been formulated in order to appreciate the contribution of the householder sex to the family and pro-capite income differentials.
description: Statistica; Vol 54, No 4 (1994)
A profile of the female cycle length
Creators: name: Cazzola, A.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: This study suggests some point of view about the menstrual cycle length. In the first part aggregate indicators of cycle characteristics are computed for various type of-data aggregations. The evidence of non-normality and positive skewness affects all data, but the choice of indicators based upon average woman-year seems to offer more regularity and bias-reduction advantages without a great loss of information. In the second part, the periodical analysis and the consequent estimated spectral density functions are applied to the basal body temperature series. These instruments are able to detect hidden periodicity's and to evaluate the relative amplitude of harmonic components of the BBT series. Obviously, the periodical analysis is an individual one, and for this reason it doesn't give us information about the overall population from which the woman was drawn, but it definitely produces unequivocal suggestions about the subset of population represented by this woman.
description: Statistica; Vol 54, No 4 (1994)
Generalized partil correlation coefficients
Creators: name: Vicari, D.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: Analysis of linear relations between two variables can be investigated in the multiway case, generalizing the Pearson correlation coefficient and defining new measures of linear dependence between matrices. In this paper, starting from the well-known partial correlation coefficient, in the same way we consider two "partial correlation" coefficients between matrices, to evaluate the strength of the linear relationship between different occasions, given the other situations.
description: Statistica; Vol 54, No 4 (1994)
Polychotomous choices and self-selection
Creators: name: Mealli, F.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: The estimation of selection models has been one of the main topic in the analysis of macroeconomics data (Heckman, 1979, 1990). They have been widely used for the estimation of treatment effects, in particular the impacts of social programs. In the paper we discuss the issues related to the assessment of treatment effects for the case where the variable of interest is binary and the selectivity is induced by a polychotomouschoice model. The problem of the identification of the effects is addressed and a parametric model presented; tests to detect the selection bias are derived. We also show how the bounds on treatment effects (Manski, 1990) can be generalized to the case of more than two treatments. An empirical example, related to the estimation of faculty effects on the drop out of university studies, concludes the paper.
description: Statistica; Vol 54, No 4 (1994)
A structural model with latent variables used to analyse the links between modernization and fertility: the case of Brazil
Creators: name: Drovandi, S.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: In the paper, a specific version of the general model with latent variabIes (LISREL) has been applied to demographic data that result from Demographic and Health Survey conducted in Brazil in 1986. The interpretative scheme used in this work has been proposed by Easterlin e Crimmins (1985). Some theories concerning the identification of latent variable indicators, used to study the relation between modernization and fertility, will be discussed. The adaptation of model (LISREL) used to analyse the links between reproductive behavior, contraceptives, economic social and cultural factors, according to the women interviewed, will be emphasized. The model provides for the individualization of links between supply and demand of child, fertility (latent endogenous variables) and female status, informative level, social and economic status, social and cultural condition (latent exogenous variables).
description: Statistica; Vol 54, No 4 (1994)
L. Boltzmann alla nascita della meccanica statistica
Creators: name: Costantini, D.
name: Garibaldi, U.
name: Penco, M. A.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: The celebrated papers giving rise to statistical mechanics that L. Boltzmann wrote between 1868 and 1877, are based on two fundamental presuppositions: first, statistical mechanics is a probabilistic theory; second, each probability distribution must be characterised in finitary terms, especially probability densities. Moreover an accurate analysis of these papers shows that Boltzmann used distributions which were unknown to contemporary statisticians, for example Beta and Gamma distributions, and that he was well aware of convergences in distribution binding them.
description: Statistica; Vol 56, No 3 (1996)
Some reasons for reconciling confidence intervals and bayesian intervals
Creators: name: Frosini, B. V.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: It is well known that one of the conflicts between Bayesian and frequentist approach to inference lies in the determination and interpretation of "interval estimates". In particular, Bayesians deny any probabilistic meaning to realised confidence intervals. On the contrary, the author shows that a confidence coefficient must inevitably be interpreted as a subjective probability, at least when there is a large uncertainty in the assignment of a prior distribution. Besides, this viewpoint is operationally sustained by some formal relationships between confidence and Bayesian intervals: exact equality between the respective coverage probabilities in some special cases (Lindley, amongst others), exact equality again between mean values of posterior probabilities and mean values of confidence coefficients in all cases (Pratt), and approximate equality between coverage probabilities in most cases, especially if the interval is calculated on a sample with a not too small size (Welch and Peers and others).
description: Statistica; Vol 56, No 3 (1996)
Estimation of the eigenvalues of the scale matrix of a class of elliptical distributions
Creators: name: Joarder, A. H.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: The simultaneous estimation of the eigenvalues of the scale matrix of a class of elliptical distributions is considered. An improved estimation strategy is developed in the light of a quadratic loss function. It is demonstrated analytically that the class of proposed estimators outperforms the class of usual estimators in the sense of having smaller risk.
description: Statistica; Vol 56, No 3 (1996)
Uno studio sulla distribuzione asintotica della metrica autoregressiva
Creators: name: Corduas, M.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: In a number of practical problems we need to group time series into homogeneous classes or clusters. In this paper we consider a parametric approach which establishes the dissimilarity between dynamic structures by means of the comparison of the corresponding linear models. In particular, we refer to the metric introduced by Piccolo (1984) on the class of ARIMA invertible models as the Euclidean distance between the weights of their Autoregressive expansions. We derive the asymptotic distribution of that criterion in the case of stationary and independent time series and show how it can be adequately approximated. A simulation study concludes the paper.
description: Statistica; Vol 56, No 3 (1996)
Transient solution of M/M/1 queues with batch arrival - a new approach
Creators: name: Gupta, R.
name: Kanwar, S.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: This paper demonstrates simple and elegant lattice path combinatorial technique for computing transient probabilities concerning M/M/1 bulk arrival queuing model. The results computed are free from generating functions and transforms. As a special case the results for ordinary M/M/1 queues are checked.
description: Statistica; Vol 56, No 3 (1996)
Longitudinal approach to poverty analysis: the latent class markov model
Creators: name: Betti, G. A.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: The aim of this work is the longitudinal analysis of the poverty phenomenon. In particular the attention is pointed out to the distinction between transitory and permanent poverty situations, which cannot be distinguished in a traditional cross-section analysis.
The empirical analysis is performed by latent class Markov models: this approach interprets poverty as a latent variable and Markov chains are used to correct measurement error in panel data. These models are used in a specific territorial context and show a good performance in fitting observed data, due to the different possible definition of restrictions as characteristics of the process under examination.
description: Statistica; Vol 56, No 3 (1996)
Companion form representation of cointegrating VARs
Creators: name: Rucchetti, L.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: In this paper the issues deriving from the companion form representation of a cointegrating Vector Autoregressive system are analysed. Spectral decomposition of the companion matrix makes it possible to derive several results (including the Granger representation theorem) in a unified framework; notably, the coefficient matrices of the VMA representation are represented in such a way that long- and short-run features of the model are clearly divided. Moreover, the method proposed lends itself quite naturally to software implementations that could improve cointegrated VAR-related algorithms by avoiding recursive formulae.
description: Statistica; Vol 56, No 3 (1996)
A simple derivation on  the chi-square approximation of  Pearson's statistic
Creators: name: Mathai, A. M.
name: Pederzoli, G.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: One of the most popular test statistics is Pearson's c2  goodness-of-fit statistic which is known to have an approximate chi-square distribution for large sample size. All the proofs so far seem to make use of the chisquaredness of quadratic forms in normal variables, manipulations of quadratic forms and singular covariance matrix. An elegant simple derivation of this result is given here without making use of chisquaredness of quadratic forms or other such results. Two numerical examples are also given to caution about the use of this statistic.
description: Statistica; Vol 56, No 4 (1996)
Stato di salute della popolazione anziana e scambi di aiuti tra generazioni
Creators: name: Pasquini, L.
name: Samoggia, A.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: The data made available by the IV cycle of the "Multiscope Survey" conducted by ISTAT were taken in order either to determine whether and in what way an elderly person who does not enjoy good health is assisted by kin, or, on the other hand, to analyse the different kind of aids supplied by elderly persons. Cluster analysis has permitted to identify eight different old-aged person profiles in relation to health status. These groups further permitted to study the levels of some variables which may give a picture of the inter-generational helping network.
description: Statistica; Vol 56, No 4 (1996)
RAQAMLI TA'LIM RESURSLARI YORDAMIDA ALGEBRA VA GEOMETRIYA ASOSLARINI MUSTAHKAMLASH
Creators: name: Sobirova, Dinora
Publisher: name: Zenodo
Year: 2025

description: Ushbu maqola raqamli ta'lim resurslaridan foydalanish orqali algebra va geometriya asoslarini o'rganish va mustahkamlashning samarali usullarini ko'rib chiqadi. Ta'lim jarayonida interaktiv dasturlar, videodarslar va testlar yordamida o'quvchilarning matematika faniga qiziqishlari oshiriladi va bilimlarni chuqurroq o'zlashtirishlariga erishiladi. Maqolada raqamli ta'lim platformalarining afzalliklari va ularni darslarda qanday qo'llash mumkinligi muhokama qilinadi.
Markov systematic sampling using auxiliary information
Creators: name: Sampath, S.
name: Uthayakumaran, N.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: In this paper, a new systematic sampling which uses both label and auxiliary information has been introduced. The suggested scheme is shown to yield positive first order inclusion probabilities for all units and positive second order inclusion probabilities for all pairs of units.
description: Statistica; Vol 56, No 4 (1996)
Un semplice test preliminare di markovianità
Creators: name: Scagni, A.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: A test of the Markov hypothesis (of arbitrary order) on an observed discrete stochastic process is often necessary before advancing further in the analysis. For this, however, a common goodness-of-fit test cannot be applied if a specific alternative is not specified, due to difficulties with its asymptotic distribution and to its computational intensity. In this paper a test based on the marginal (w. r. to time) distributions of the process is proposed. Specifically, a Wald-type test is developed after computing the general variance-covariance matrix for observed frequencies in any two different times t~ and t2, obtained from a Markov chain of arbitrary order m. Similarities with the literature on goodness-of-fit tests for complex samples are also investigated, since the marginal (w. r. to time) distributions of the process can be seen as generated by a cluster sampling scheme. Such at test has also to be performed before the application of the multivariate Markov chain models considered in Scagni (1993).
description: Statistica; Vol 56, No 4 (1996)
L'analisi della domanda dei flssi turistici: specificazione e stima di un modello "Almost ideal demand system"
Creators: name: Costa, M.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: International tourism analysis is performed on the demand side, referring to the AIDS model, which consents to test the main hypotheses concerning consumer behaviour. Moreover, expenses on holidays abroad are considerably influenced by income and relative prices. By testing homogeneity and symmetry hypotheses some relevant differ-ences between the UE countries are detected. Finally, prices elasticites provide evi-dence about the relation between domestic prices and holidays abroad and about the interrelation among prices of different destinations.
description: Statistica; Vol 56, No 4 (1996)
La specifcazione di un modello per la previsione della domanda turistica mediante reti neurali
Creators: name: Guizzardi, A.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: In this paper aggregate tourist demand is modelled by the sum of a long term component, related to extra-economic factors, and a short term component, related to economic dynamics. For the latter a specification strategy is proposed that does not imply the choice of a particular functional form. This is made possible by the use of a neural networks model. As an example of empirical application, we define the intertemporal relationship among variables like exchange rate, income and unemployment and the short term component of tourist demand on the Emilia Romagna coast.
description: Statistica; Vol 56, No 4 (1996)
Establishing a comprehensive search strategy for Indigenous health literature reviews
Creators: name: Harding, Louise
name: Marra, Caterina J.
name: Illes, Judy
Publisher: name: BioMed Central
Year: 2021

description: Background: Appropriate search strategies are essential to ensure the integrity and reproducibility of systematic and scoping reviews, as researchers seek to capture as many relevant resources as possible. In the case of Indigenous health reviews, researchers are met with the special challenge of creating a search strategy that can encompass this large, diverse population group with no universally agreed upon identification criteria. Main body: With an aim to promote improved review methodologies that uphold standards of justice, autonomy, and equity for Indigenous peoples and other heterogeneous populations, we describe critical gaps and approaches to close them. We report organizational and transparency issues around how Indigenous populations are indexed in several major databases, and draw on examples of published reviews and protocols to demonstrate the challenges inherent to creating a comprehensive search strategy. Conclusions: The conduct and communication of results from health literature research on global Indigenous populations are compromised by challenges of methodology that are rooted in the complexities inherent to defining Indigenous peoples. These challenges must be urgently addressed to improve this important field of inquiry moving forward.
Le famiglie di censimento sono famiglie di fatto? Famiglie unipersonali e monogenitore al censimento
Creators: name: Gerondi, C.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: The aim of this paper is to appraise the impact at the 1991 Italian Population Census of the households composed by married people who do not live together, assuming they represent an overvaluation of the households which have been registered as one parent families or as no-families (one person).
description: Statistica; Vol 56, No 4 (1996)
The numerical analysis of patient-specific human heart towards the design of the next-generation ventricular assist device
Creators: name: Nezami Doost Alamdari, Siamak
Publisher: name: Swinburne
Year: 2024

description: The blood flow within normal and impaired hearts has been simulated using CFD technique in conjunction with cardiovascular MRI images to extend our knowledge of the cardiac blood circulation. Information captured by numerical simulation plays a pivotal role in providing insight for clinicians to fully understand the blood circulation, and probably, in the future, will be utilized as a diagnostic tool. Additionally, the idea of a novel next-generation ventricular assist device (VAD) has been extended in this study, which we believe it may provide a promising avenue for the manufacture of future generations of VAD.
The uniform difference association-multivariate Logit model
Creators: name: Colombi, R.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: The Goodman Association Model and its generalization called Uniform Difference Association Model are well known for their flexibility in modelling the association between two categorical variables and for the graphical displays that can be obtained from the estimates of their parameters, but these models are not appropriate if the focus of the investigation is in modelling the marginal probabilities. This is so because these models imply complicate parametric expressions for the marginal probabilities. Having in mind that a simple parameterization of the marginal probabilities is often desirable a modification of the Uniform Difference Association Model is proposed, in order to obtain a model, that allows a simple parameterization of the marginal probabilities, and models the association between categorical variables in the same way followed by the Goodman Association Model and the Uniform Difference Association Model. For the proposed model, it shown how the maximum likelihood estimates of the parameters can be computed. The properties of the maximum likelihood estimators are discussed as well. Finally a generalization to the case of more than two categorical variables is discussed.
description: Statistica; Vol 57, No 1 (1997)
A method of analysing subgroup poverty using a new decomposition of the Gini coefficient
Creators: name: Podder, N.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: This paper analyses the properties of the Sen measure of poverty and then decomposes the measure by subgroups of population. It is shown that total poverty is the simple sum of the shares of all subgroups poverty or it is the weighted sum of within group poverty. The method is based on the disaggregation of the Gini coefficient among subgroups developed by Podder (1993) earlier. It is demonstrated that the decomposition satisfies the subgroup consistency in the sense that if poverty in a subgroup reduces by a certain degree, overall poverty must reduce by the same degree. The decomposition presented here is shown to be useful in answering important questions regarding the nature of poverty in a society. Thus, it extends the usefulness of the Sen measure in empirical research.
description: Statistica; Vol 57, No 1 (1997)
Amortization method with stochastic indexation of the outstanding principal
Creators: name: Cerè, M.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: In this paper we present a model of a debt's amortization with stochastic indexation of the outstanding principal. We first introduce a stochastic differential equation which allow us to define the inflation and deflation process. Then we use these concepts to present a new method of redemption quota calculation, based on the equality between backward outstanding principal and conditional expectation of the forward outstanding principal. Finally numerical examples illustrate the model.
description: Statistica; Vol 57, No 1 (1997)
A microsimulation model of Dutch tourist behaviour an exploration of Dutch panel data
Creators: name: Brouwer, N. M.
name: Brouwer, E.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: In this paper the holiday behaviour of the Dutch population is described, using Dutch panel data. Several econometric models have been applied and the results of these models have been compared. A Tobit model with heteroscedasticity has been selected as the best specification, and the results of this specific model have been used to construct a microsimulation model (MSM). The paper shows that microsimulation is a rich instrument to describe the (changes in) participation probability and holiday expenditure of Dutch households.
description: Statistica; Vol 57, No 1 (1997)
Graph- and multigrafh-theoretic partitioning clustering algorithms for large data sets
Creators: name: Soffritti, G.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: This work aims at introducing two clustering algorithms conceived to make the application of particular graph and multigraph theoretic clustering methods possible for large data sets. Results obtained by applying the suggested algorithms to simulated data sets are presented.
description: Statistica; Vol 57, No 1 (1997)
Conditions for Maximum Operating Efficiency of a Multi-Junction Solar Cell and a Proton Exchange Membrane Electrolyser System for Hydrogen Production
Creators: name: Gies, Warren
Publisher: name: Université d'Ottawa / University of Ottawa
Year: 2020
Subjects: Solar
Hydrogen
Electrolyser
Efficiency
Multi-junction
Concentrator

description: Hydrogen is a valuable and versatile energy currency; it may be produced by harvesting solar energy and later used as a fuel to generate electricity any time of the day. This energy transaction of solar energy to hydrogen is evaluated in this work by employing a one-to-one multi-junction solar cell to proton exchange membrane combined system in a laboratory setting. Both components of the system were commercially available. The energy conversion efficiency of each isolated system was first evaluated to determine the ideal operation conditions of each respective system. For input currents in the range of 60 mA to 440 mA, the proton exchange membrane converted electrical energy to chemical potential energy with an efficiency greater than 90%. The multi-junction solar cell reached efficiencies of up to 33% while under a solar concentration of 30 Suns. The current and voltage characteristics, which resulted in the optimal operation of the isolated systems did not align and therefore, both systems were not operating at their ideal operation conditions when in the combined system. The overall energy conversion efficiency of the system was measured to be at most 19.1% under 25 Suns, an efficiency higher than systems employing traditional silicon solar cells. It was theorized that if the two system were operating under ideal conditions, the overall energy conversion efficiency would be 30.3% between 10 and 15 Suns. Methods to align the ideal operation conditions of the two systems are presented.
Atmega Based Vehicle Theft and Engine Lock System
Creators: name: Abu Sabir K V, Jithin J, Mohammed Nihal A, Srikanth K
Publisher: name: Zenodo
Year: 2024

description: The "ATmega-Based Vehicle Theft and Engine Lock System" integrates an ATmega microcontroller for robust vehicle security. It enables users to remotely manage engine status via SMS commands and receives real-time GPS updates for accurate location monitoring. Upon activation, the system initiates monitoring of the vehicle's whereabouts and awaits user commands via SMS. It proactively alerts users whenever the engine is activated, enhancing theft prevention measures. This system combines the reliability of ATmega microcontrollers with GPS technology to provide effective vehicle security and peace of mind for users concerned about theft and unauthorized use of their vehicles.
Statistical inference from an axiomatic viewpoint
Creators: name: De Cristofaro, R.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: The introduction of the axioms of utility led many statisticians to think that there is only one correct statistical inference, that which complies with the results of decision theory. In reality, every theory comes to conclusions which require choices which in turn have unavoidable pragmatic consequences. But, since the axioms of a theory are accepted, it is self-sufficient. The truth of its results is relative to our conventions. We can discuss these conventions, but, unless the assumptions are changed from the very beginning, the solution to the problem of statistical inference must be found within probability calculus. On the other hand, if we accept de Finetti's coherence principle, then the usual assumptions of probability theory and the consequent rules of inference (Bayes' role included) appear inevitable. In this context, we agree with Lindley (1990), "according to this view, all manipulations in inference are solely and entirely within the calculus of probability. The mathematics is that of probability". However, following an axiomatic viewpoint, we go to a further conclusion and we agree with Carnap that statistical inference can be regarded as a simple inductive inference.
The axiomatic approach to statistical inference has not yet received a sufficient attention in Statistics. Many prejudices remain in this area. In particular, the claims of superiority of testing and other decisional procedures are unjustified. An exhaustive analysis of the process of the updating of probabilities may allow us to correct the distortions due to an acritical application of theories in which the inferential situation is examined in a particular context. In line with these ideas, in this paper statistical inference is consistently developed from a pure Bayesian viewpoint. The approach is then illustrated by means of some numerical examples.
description: Statistica; Vol 57, No 1 (1997)
Spatial regressive and autoregressive models with SARMA error terms
Creators: name: Lafratta, G.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: The aim of this paper is to define and to analyse classes of models satisfactory for the consideration of the spatial effects of dependence and heterogeneity. In particular, we introduce the ADL-N (Autoregressive Distributed Lags - Noise) class in order to model sets of spatial data. This class consists of a generalization of the well known class of the ADL (Hendry et al., 1984) models, introduced in the analysis of time series. This generalization is obtained by means of the hypothesis that the error component is generated by a spatial ARMA process (Cressie, 1993). It is well known that the multilateral dependence, which characterizes spatial processes, results in correlation between the endogenous variable and the disturbance term in the model, causing the inconsistency of ordinary least squares estimators (Anselin, 1988). The model we propose is based upon the use of the conditional likelihood function to obtain consistent and asymptotically efficient estimators for the model's parameters. In the paper we report the gradient and the Hessian matrix of the log-likelihood function for the model proposed. To perform hypothesis testing, we have coded two procedures to test ML (Maximum Likelihood) estimation results, termed respectively OLT (Omitted Lags Test) and DLT (Deleted Lags Test). The latter tests the hypothesis that a component introduced in the model is inconsistent with the data; the former tests that a component not still introduced is - on the contrary - consistent with the data. All these procedures need the use of the Fisher Information matrix, which is reported for the ADL-N class of models.
description: Statistica; Vol 57, No 1 (1997)
Discrete state transition models in exploratory research
Creators: name: Contini, D.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: The paper deals with discrete state transition models in the context of exploratory research, where robust methods are required and particular interest lies on covariate coefficients. If there is unobserved heterogeneity, Cox's partial likelihood estimators are inconsistent, and models that completely specify the likelihood, including autocorrelation mechanism of heterogeneity components, are not robust. Separate estimation of likelihood terms regarding spells of different order does not require specification of the autocorrelation pattern among heterogeneity components, but inconsistent estimates are generally produced. Conditions for consistency and efficiency of this method are given. A more robust separate estimation strategy is proposed. It can be applied if the length of the observation period is a random variable independent from the process under study. The application deals with histories of heroin addiction of patients in charge of a public rehabilitation centre, from the beginning of treatment thereon.
description: Statistica; Vol 57, No 1 (1997)
Telomere Architecture Correlates with Aggressiveness in Multiple Myeloma
Creators: name: Rangel-Pozzo, Aline
name: Yu, Pak Lok Ivan
name: LaL, Sadhana
name: Asbaghi, Yasmin
name: Sisdelli, Luiza
name: Tammur, Pille
name: Tamm, Anu
name: Punab, Mari
name: Klewes, Ludger
name: Louis, Sherif
name: Knecht, Hans
name: Olujohungbe, Adebayo
name: Mai, Sabine
Publisher: name: Multidisciplinary Digital Publishing Institute
Year: 2021

description: The prognosis of multiple myeloma (MM), an incurable B-cell malignancy, has significantly improved through the introduction of novel therapeutic modalities. Myeloma prognosis is essentially determined by cytogenetics, both at diagnosis and at disease progression. However, for a large cohort of patients, cytogenetic analysis is not always available. In addition, myeloma patients with favorable cytogenetics can display an aggressive clinical course. Therefore, it is necessary to develop additional prognostic and predictive markers for this disease to allow for patient risk stratification and personalized clinical decision-making. Genomic instability is a prominent characteristic in MM, and we have previously shown that the three-dimensional (3D) nuclear organization of telomeres is a marker of both genomic instability and genetic heterogeneity in myeloma. In this study, we compared in a longitudinal prospective study blindly the 3D telomeric profiles from bone marrow samples of 214 initially treatment-naïve patients with either monoclonal gammopathy of undetermined significance (MGUS), smoldering multiple myeloma (SMM), or MM, with a minimum follow-up of 5 years. Here, we report distinctive 3D telomeric profiles correlating with disease aggressiveness and patient response to treatment in MM patients, and also distinctive 3D telomeric profiles for disease progression in smoldering multiple myeloma patients. In particular, lower average intensity (telomere length, below 13,500 arbitrary units) and increased number of telomere aggregates are associated with shorter survival and could be used as a prognostic factor to identify high-risk SMM and MM patients.
Start-up size,survival and growth of new firms in the Italian tourism industry
Creators: name: Santarelli, E.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: This paper analyses the link between the survival and growth of new firms in Italian tourism services and their start-up size. While in most regions the likelihood of survival is found to be significantly influenced by start-up size, Gibrat's Law turned out to hold for most regions, in contrast to the results reported by several authors for other sectors and countries. This implies that whereas larger newborn firms in the tourism sector have in most Italian regions a higher probability of survival than their smaller counterparts, the probability of a proportionate change in size during the relevant period is the same for all firms in most regions.
description: Statistica; Vol 57, No 1 (1997)
The plural form of  "index number" in the Italian language
Creators: name: Predetti, A.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: Facing two possible plural (Italian) forms for "index number" ("numeri indici" and "numeri indice"), the author explains his preference for the first one.
description: Statistica; Vol 57, No 1 (1997)
Realistic interpretations of de Finetti's Theorem
Creators: name: Garibaldi, U.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: Mixtures of binomial distributions have been recently introduced in Statistical Physics both in theoretical and in experimental frames in order to explain physical correlations. The physical interpretation of the mixing distribution is realistic, in contrast with the subjective mood originally attached by De Finetti to his celebrated "Representation Theorem". Inductive and physical correlations, despite different in meaning, obey the same mathematical rules. Hence the logical status of the Theorem is worth of reconsideration by non-bayesian statisticians.
description: Statistica; Vol 57, No 2 (1997)
On hermitian bilinear forms in complex normal variables
Creators: name: Sultan, S. A.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: Bilinear forms in complex normal variables when matrices of the forms are rectangular are considered. Expressions for the cumulants, joint cumulants of arbitrary order of hermitian bilinear and hermitian quadratic forms are given. Necessary and sufficient conditions for the independence of two hermitian bilinear forms and a hermitian bilinear and a hermitian quadratic form are stated.
description: Statistica; Vol 57, No 2 (1997)
Survival functions and mortality tables at the origins of actuarial mathematics
Creators: name: Spelta, D.
Publisher: name: Dep. of Statistical Sciences "Paolo Fortunati", Università di Bologna
Year: 2013

description: In the determination of death probabilities of an insured subject one can use either statistical data or a mathematical function. In this paper a survey of the relationship between mortality tables and survival functions from the origins until the first half of the nineteenth century is presented. The author has tried to find the methodological grounds which have induced the actuaries to prefer either of  these tools.
description: Statistica; Vol 57, No 2 (1997)