Search results for " Statistics"
showing 10 items of 1891 documents
Combining Sequence Analysis and Hidden Markov Models in the Analysis of Complex Life Sequence Data
2018
Life course data often consists of multiple parallel sequences, one for each life domain of interest. Multichannel sequence analysis has been used for computing pairwise dissimilarities and finding clusters in this type of multichannel (or multidimensional) sequence data. Describing and visualizing such data is, however, often challenging. We propose an approach for compressing, interpreting, and visualizing the information within multichannel sequences by finding (1) groups of similar trajectories and (2) similar phases within trajectories belonging to the same group. For these tasks we combine multichannel sequence analysis and hidden Markov modelling. We illustrate this approach with an …
The ALHAMBRA survey: B -band luminosity function of quiescent and star-forming galaxies at 0.2 ≤ z < 1 by PDF analysis
2016
[Aims]: Our goal is to study the evolution of the B-band luminosity function (LF) since z ∼ 1 using ALHAMBRA data. [Methods]: We used the photometric redshift and the I-band selection magnitude probability distribution functions (PDFs) of those ALHAMBRA galaxies with I ≤ 24 mag to compute the posterior LF. We statistically studied quiescent and star-forming galaxies using the template information encoded in the PDFs. The LF covariance matrix in redshift - magnitude - galaxy type space was computed, including the cosmic variance. That was estimated from the intrinsic dispersion of the LF measurements in the 48 ALHAMBRA sub-fields. The uncertainty due to the photometric redshift prior is also…
Motivic Pattern Extraction in Music, and Application to the Study of Tunisian Modal Music
2007
A new methodology for automated extraction of repeated patterns in time-series data is presented, aimed in particular at the analysis of musical sequences. The basic principles consists in a search for closed patterns in a multi-dimensional parametric space. It is shown that this basic mechanism needs to be articulated with a periodic pattern discovery system, implying therefore a strict chronological scanning of the time-series data. Thanks to this modelling global pattern filtering may be avoided and rich and highly pertinent results can be obtained. The modelling has been integrated in a collaborative pro ject between ethnomusicology, cognitive sciences and computer science, aimed at the…
A Bayesian spatio‐temporal analysis of markets during the Finnish 1860s famine
2022
We develop a Bayesian spatio-temporal model to study pre-industrial grain market integration during the Finnish famine of the 1860s. Our model takes into account several problematic features often present when analysing multiple spatially interdependent time series. For example, compared with the error correction methodology commonly applied in econometrics, our approach allows simultaneous modelling of multiple interdependent time series avoiding cumbersome statistical testing needed to predetermine the market leader as a point of reference. Furthermore, introducing a flexible spatio-temporal structure enables analysing detailed regional and temporal dynamics of the market mechanisms. Appl…
Calculating the implied correlation matrix for a Path Analysis model
2014
To overcome the limitations of two existing methods for calculating a Path Analysis implied correlation matrix, this paper presents an alternative method for calculating this matrix. This new method is based on a recurrence principle which is easy and quick to implement. This method is also operational regardless of the number of variables. The consequences of this result with the estimation or testing stages will be illustrated on the basis of examples.
PISA y TALIS ¿congruencia o discrepancia?
2016
Las evaluaciones educativas internacionales a gran escala ofrecen información de interés para la comunidad educativa, científica y política. Son muchos los estudios derivados de ellas, tanto a nivel nacional como internacional. Por otra parte, es bien conocida, desde el origen de estas macroevaluaciones, la diversidad de valoraciones que han generado. En este contexto, el objetivo del trabajo que aquí se presenta es estudiar las relaciones entre los resultados de PISA 2012 y los relativos a práctica docente de secundaria de TALIS 2013, tratando de analizar las congruencias o discrepancias entre los resultados de ambas. Se tomaron los datos del estudio TALIS-PISA link. Los análisis realizado…
Multi-destination trips: A survey on incoming zourism in Sicily
2012
Many pleasure trips are often characterized by the visit of more than a single destination. Despite the topic is well documented in literature, the empirical studies are limited to a few pioneering studies. This lack may be attributable to the failure of tourism organizations to collect data on multi-destination trip behaviors, as it results, for example, from the system of European statistics on tourism (according to the Council Directive 95/57 EC), where no information on the average number of destinations visited within a single trip are provided. This paper aims to analyze the main implications of multi-destination trips both on tourism statistics and in tourism planning, and to describ…
Insights into the derivative-based method for nonlinear mediation models
2022
Associational mediation analysis has generally relied on the linearity of models to estimate the indirect effect as a product of regression coefficients. Very few examples of generalisations to nonlinear settings have been proposed, including a derivative-based method that, however, is far from being widely spread among scholars. In this paper, we clarify some aspects of such an approach to nonlinear mediation models, which have not been addressed by the previous literature. In addition, we run a simulation study to compare confidence intervals for the indirect effect obtained through different approaches.
Kinetic analysis of functional images: The case for a practical approach to performance prediction
1999
We present the first parallel medical application for the analysis of dynamic positron emission tomography (PET) images together with a practical performance model. The parallel application may improve the diagnosis for a patient (e. g. in epilepsy surgery) because it enables the fast computation of parametric images on a pixed level as opposed to the traditionally used region of interest (ROI) approach which is applied to determine an average parametric value for a particular anatomic region of the brain. We derive the performance model from the application context and show its relation to abstract machine models. We demonstrate the accuracy of the model to predict the runtime of the appli…
El Instituto Médico Valenciano y la difusión de la vacuna
2004
The Medical Valencian Institute promoted a campaign of smallpox free vaccination (1851- 1894) by means of humanized vaccine sent from England. It spread the vaccination for the whole Spain and published careful statistics of the vaccinations practised in the Bulletin of the Medical Valencian Institute. The National Institute of Vaccination (1871) did not recognize his labor and one denied to him the category of Provincial Institute of Vaccination.