Search results for "Statistica"
showing 10 items of 5969 documents
Comparison of non-Markovianity criteria in a qubit system under random external fields
2013
We give the map representing the evolution of a qubit under the action of non-dissipative random external fields. From this map we construct the corresponding master equation that in turn allows us to phenomenologically introduce population damping of the qubit system. We then compare, in this system, the time-regions when non-Markovianity is present on the basis of different criteria both for the non-dissipative and dissipative case. We show that the adopted criteria agree both in the non-dissipative case and in the presence of population damping.
Establishing Equivalence or Non-Inferiority in Clinical Trials
2012
Background: An increasing number of clinical trials are being performed to show the absence of relevant differences between the effects of two treatments. The primary care physician makes use of the results of so-called equivalence studies, at least indirectly, practically every day. Equally important are active control clinical trials in which the efficacy of a new treatment has to be proven through demonstrating non-inferiority as compared to a standard treatment. Methods: Explanation of basic principles and statistical techniques with reference to the original literature; selective searches in the medical literature. Results: First of all, a suitable distributional parameter must be chos…
Dimensional Latent Structure of Relationship Quality: Results of Three Representative Population Samples
2015
One central issue for every latent construct in psychology (e.g., relationship quality) is its latent nature: Differences in intelligence, for example, are traditionally considered to be dimensional (e.g., when quantifying intelligence by a standardized test score) rather than categorical (distinguishing different categories such as intelligent vs. unintelligent). When considering a categorical construct, such as Down syndrome, on the other hand, the characteristic is qualitative (groups are classified by existence or absence of an extra chromosome) rather than quantitative (varying degrees of Down syndrome). The group bound together by the possession of a certain characteristic (disease, d…
Does taking additional Maths classes in high school affect academic outcomes?
2023
Several studies in the mathematical education literature show the effect of students’ high school skills in maths on their success at higher levels of education and work. In particular, the importance of maths course taking in US high schools is highlighted to be important for college enrolment and completion. The choice of taking additional maths courses or, as in Italy, of choosing a high-school curriculum with more maths, is not random: it depends on several substantial factors such as gender and socio-economic status. This selection bias implies that the differences in the academic outcomes might be traceable not only to mathematics ability and knowledge. In this paper, the aim is to es…
Statistical methods for the evaluation of university systems
2011
A note on (basic) Principal Components Analysis
2020
This paper provides some issues, known but somewhat little stressed, on using the conventional covariance or correlation matrix when performing the simple PCA. The paper also proposes a new simple alternative by providing some evidence, via real-data analysis and some simulation experiments, supporting the proposal
Il modulo elastico statico e dinamico del calcestruzzo
2012
L’emigrazione dei laureati dalla Sicilia: le più recenti evidenze statistiche
2008
Coarse-Graining Intermolecular Interactions in Dispersions of Highly Charged Colloids
2012
International audience; Effective pair potentials between charged colloids, obtained from Monte Carlo simulations of two single colloids in a closed cell at the primitive model level, are shown to reproduce accurately the structure of aqueous salt-free colloidal dispersions, as determined from full primitive model simulations by Linse et al. (Linse, P.; Lobaskin, V. Electrostatic Attraction and Phase Separation in Solutions of Like-Charged Colloidal Particles. Phys. Rev. Lett.1999, 83, 4208). Excellent agreement is obtained even when ion-ion correlations are important and is in principle not limited to spherical particles, providing a potential route to coarse-grained colloidal interactions…
Profilo Strategico e scelte innovative nelle imprese del settore manifatturiero siciliano
2013
In 1959, Penrose highlighted how the firm's organisation of economic activity is based on its perception about the adjustment of production to the market, more than on objective evaluation. So, she underlined not just the importance to identify the nature of the determinants about firm behaviour, but also how the assessment of these factors must consider the production context where they originate. Now, this context for Penrose has to be considered as an image in the mind of the entrepreneur of the possibilities and restrictions of the market. In line with this view, and with the recent approach to innovation policies, this work analyses the survey data collected in 2008 on the innovation n…