Search results for "Statistica"

Statistical Modelling and Risk Analysis of Bitcoins Exchange Rate

2018

Master's thesis Business Administration BE501 - University of Agder 2018 Bitcoin is a phenomenon that is new and there is little information on how and why it behaves as volatile as it does. This thesis uses existing data on Bitcoin’s exchange rate to estimate a model that describes the pattern and use it in a financial risk analysis. We also aim to contribute as a foundation for further studies in this field. The statistical properties of the log-return of the exchange rate are analysed and it is deemed to be iid. From the eleven distributional candidates we study is the fitted skew generalised t distribution proven to represent the data best after evaluation by criteria and statistics. Th…

Indicators for Tourist Destinations: A General Assessment

2022

The assessment and monitoring of tourist destinations is now more than ever a prerogative of governments around the world. The contiguous situation caused by the outbreak of the COVID-19 pandemic is pushing local destinations to adopt new standards that have never been considered until now. In addition, the collapse of tourist demand and the partial recovery of tourist activities could, in the medium term, affect tourist flows, but more importantly the tourist supply, which still suffers from suppliers and producers damaged by the blockage of services and production. The work aims to provide a general assessment of sustainability and competitiveness indicators, describing the work carried o…

Viaggi multi-destinazione in Sicilia: principali determinanti ed effetti distorcenti nelle statistiche sul turismo

2013

Pareto frontier in economic-statistical design of a dynamic c chart

2015

The present paper proposes an economic-statistical multi-objective design procedure for a dynamic c control chart. In detail, a mixed integer non-linear constrained mathematical model is formulated to solve the treated problem, whereas the Pareto frontier is described by the ε-constraint method. To show the employment of the proposed procedure a numerical case is solved and the related considerations are given.

An Emulator Toolbox to Approximate Radiative Transfer Models with Statistical Learning

2015

Physically-based radiative transfer models (RTMs) help in understanding the processes occurring on the Earth’s surface and their interactions with vegetation and atmosphere. When it comes to studying vegetation properties, RTMs allows us to study light interception by plant canopies and are used in the retrieval of biophysical variables through model inversion. However, advanced RTMs can take a long computational time, which makes them unfeasible in many real applications. To overcome this problem, it has been proposed to substitute RTMs through so-called emulators. Emulators are statistical models that approximate the functioning of RTMs. Emulators are advantageous in real practice because…

Longitudinal mediation analysis with structural and multilevel models: associational and causal perspectives

2022

Analysing SET over time using multilevel multidimensional explanatory IRT models

2013

This contribution makes an attempt to analyze students' ratings of university teaching on a broad prospective, trying to adjust the final assessment from a wide range of factors which jointly may influence the process under evaluation: academic year peculiarities, course characteristics, students' characteristics and item dimensionality. From a methodological point of view, by setting complex Item Response models as special case of Generalized Linear or Mixed Models a large flexibility is introduced in the specification of ad hoc modelling approaches for the analysis of students' ratings.

Socio-Demographic Vulnerability of Youth

2008

For a kind of inertia effect, the Italian welfare state protects today the old age too intensely while little the new risks associated with other phases of life course. Young Italians seem to suffer the actual changes: “youth remain longer in parental home and postpone the creation of its own independent life to most advanced age”. To understand the vulnerability situation increasingly widespreading among young people, it seems more and more necessary the depth analysis of the reasons and the subjective status of this discomfort that occur through a delay in transition to adulthood. In particular we study the self-perceived vulnerability situation of young Italians in the labor market (both…

STUDY OF LARGE PELAGIC FISH LIFE-HISTORY TRAITS IN THE CENTRAL MEDITERRANEAN SEA AND PROJECTION UNDER FUTURE CLIMATE CHANGE SCENARIOS

2022

One of the most sensitive life periods for each species is the first life stages (larval and juvenile). The survival rates of pelagic fish larvae in these phases are usually very low and subject to fluctuations, consequently affecting the recruitment of new generations. From historical Tuna landing data, the stock's abundance is fluctuating, especially for Atlantic Bluefin Tuna (ABT) (Thunnus thynnus, Linnaeus, 1758) Eastern stock. It is the largest Mediterranean Tuna and one of the most expensive species in the world. Some studies hypothesized that the fluctuations are dictated by environmental factors, particularly in the early life stages. Therefore, it appears necessary to better unders…

Unveiling the Relationship Between Sea Surface Hydrographic Patterns and Tuna Larval Distribution in the Central Mediterranean Sea

2021

Thunnus thynnus (Atlantic bluefin tuna, ABT) and other tuna species reproduce in the Mediterranean Sea during the summer period. Despite the Central Mediterranean Sea, the Strait of Sicily in particular, being a key spawning site for many tuna species, little is known on the effects of oceanographic variability on their larval distribution in this area. The abundance and presence-absence of larval specimens for three tuna species (ABT, bullet tuna and albacore) were modeled in order to examine their relationships with environmental factors, by analysing historical in situ information collected during seven annual surveys (2010–2016). The results revealed that most tuna larvae for the three …