Search results for " Statistics"

Comment améliorer la prévision des ventes pour le marketing ? Les apports de la théorie du chaos

2013

La littérature en marketing constate un décalage entre les avancées réalisées par les chercheurs qui développent de nouvelles méthodes de prévision des ventes, et l'usage massif de méthodes traditionnelles reposant sur l'hypothèse de linéarité des processus analysés. Cette recherche expose la contribution potentielle de la théorie du chaos à l'amélioration de la prévision des ventes. Une illustration de ces apports est proposée avec une application à la prévision des ventes de consoles de jeux vidéo au Japon. Les résultats mettent en évidence la capacité de la méthode proposée à détecter la présence de chaos dans la série et montrent la possibilité de préciser l'horizon de prévisibilité des…

How many longitudinal covariate measurements are needed for risk prediction?

2014

Abstract Objective In epidemiologic follow-up studies, many key covariates, such as smoking, use of medication, blood pressure, and cholesterol, are time varying. Because of practical and financial limitations, time-varying covariates cannot be measured continuously, but only at certain prespecified time points. We study how the number of these longitudinal measurements can be chosen cost-efficiently by evaluating the usefulness of the measurements for risk prediction. Study Design and Setting The usefulness is addressed by measuring the improvement in model discrimination between models using different amounts of longitudinal information. We use simulated follow-up data and the data from t…

Understanding beginners' mistakes with Haskell

2015

AbstractThis article presents an overview of student difficulties in an introductory functional programming (FP) course taught in Haskell. The motivation for this study stems from our belief that many student difficulties can be alleviated by understanding the underlying causes of errors and by modifying the educational approach and, possibly, the teaching language accordingly. We analyze students' exercise submissions and categorize student errors according to compiler error messages and then manually according to the observed underlying cause. Our study complements earlier studies on the topic by applying computer and manual analysis while focusing on providing descriptive statistics of d…

The challenges of GxE research: A rejoinder

2017

A Cluster Analysis Approach to Profile Men and Women’s Volley Positions in Professional Tennis Matches (Doubles)

2021

(1) Background: Tennis ball tracking technology allows the aquirement of novel and reliable data about several performance indicators, such as volley positions. This information is key to understand match dynamics in doubles tennis and to better help preparing players for the demands they will face in match play. As such, the purpose of this study was to describe and compare the different types of volley positions in men’s and women’s doubles professional tennis. (2) Methods: Ball tracking data were collected for 46 women (Billie Jean King Cup) and 96 men’s doubles matches (Davis Cup). The variables used were the distance to the net, the distance to the centre of the court and the height of…

A Time-Non-Homogeneous Double-Ended Queue with Failures and Repairs and Its Continuous Approximation

2018

We consider a time-non-homogeneous double-ended queue subject to catastrophes and repairs. The catastrophes occur according to a non-homogeneous Poisson process and lead the system into a state of failure. Instantaneously, the system is put under repair, such that repair time is governed by a time-varying intensity function. We analyze the transient and the asymptotic behavior of the queueing system. Moreover, we derive a heavy-traffic approximation that allows approximating the state of the systems by a time-non-homogeneous Wiener process subject to jumps to a spurious state (due to catastrophes) and random returns to the zero state (due to repairs). Special attention is devoted to the cas…

TimeSens - un logiciel Web pour l'acquisition et le traitement des données sensorielles

2010

TimeSens est un nouveau logiciel dédié à l'acquisition et au traitement des données d'analyse sensorielle. TimeSens bénéficie de l'expérience et de l'expertise de ChemoSens, la plate-forme d'analyse sensorielle du CSGA. TimeSenspropose la plupart des protocoles standards de l'analyse sensorielle (profil, tests hédoniques, DTS), ainsi que des protocoles originaux (MATI, PSP). Les résultats collectés peuvent être analysés à l'aide de méthodes statistiques traditionnelles ou innovantes.

Unobserved Tourism: Conceptual Aspects and Estimates

2013

Analysing tourist mobility: current issues and future challenges

2013

Tourism statistics are generally based on data collected only at one point of the travel, which, depending on the perspective of interest, can be the originating region or the destination one. Indeed, many tourism trips imply the visit to more than a single destination, since tourists move to visit several attraction to several destination or within the same destination. The analysis of tourist mobility presents several issues which are related both to the collection of information on multidestination trip behaviour and to the analysis of complex information such as the ones related with tourist itineraries. The present work aims at reviewing the main issues related with the analysis of tou…

Multi-destination trips: a survey on incoming tourism 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…