Search results for "ESTIMATION"

Crash modeling for urban roundabouts: a case study

2013

In many cities and towns, a large number of intersections are considered sites with promise for safety and operational improvements. Several studies have been carried out in many countries to establish relationships between crashes and flow and non-flow explanatory variables, using statistical tools to investigate factors critical to road safety. Starting from a brief review of existing information and analysis on the issue, this article summarizes the findings of an exploratory analysis aimed at modeling injury crashes for a sample of urban roundabouts. The methodological path followed in this research allowed to handle issues associated with the estimation of a safety performance function…

Production Function Estimation in Stata Using the Ackerberg–Caves–Frazer Method

2016

We present a new e-class command, acfest, that implements the method of Ackerberg, Caves, and Frazer (2015, Econometrica 83: 2411–2451) to estimate production functions. This method deals with the functional dependence problems that may arise in the methods proposed by Olley and Pakes (1996, Econometrica 64: 1263–1297) and, particularly, Levinsohn and Petrin (2003, Review of Economic Studies 70: 317–341) (implemented in Stata by Yasar, Raciborski, and Poi [2008, Stata Journal 8: 221–231] and Petrin, Poi, and Levinsohn [2004, Stata Journal 4: 113–123], respectively). In particular, the acfest command yields (nonlinear, robust) generalized method of moments estimates using a Mata function an…

Estimation of selected skin parameters during a series of beauty treatments in women with acne: a pilot study

2021

Background: Acne vulgaris occurs most often in young people and can significantly decrease the quality of life. Properly selected dermatological therapy and cosmetic procedures can effectively improve the skin condition of acne patients. Aim of the study: The aim of this study was to examine how various cosmetics treatments affect facial sebum levels, skin hydration, and desquamation in young women with acne vulgaris. Material and Methods: 101 women with acne aged 19–29 (M = 22.5 years, SD = 2.3 years) were included in the study. The following cosmetic treatments were used over a 12-week period: intensive pulsing light, alpha-hydroxy acids, cavitation peeling, non-needle mesotherapy, diamon…

Methods to Use Big Wearable Heart Rate Data for Estimation of Physical Activity in Population Level

2015

Technologies for wearable health monitoring are becoming increasingly popular and affordable. As a result, large-scale health databases from a large number of individuals are becoming available. However, analysis of these databases requires special methodology to transform available parameters into more generic ones and to manage such non-balanced data characteristics as biases and sampling issues. In this paper, we introduce a methodology for studying physical activity from big wearable heart rate (HR) data on about 5 000 working-age individuals, each measured only for a few days. Physical activity was assessed by oxygen consumption (VO2) calculated from measured HR data using a neural net…

The errors in ?estimation of errors in mechanical efficiency?

1992

2014

Depressed patients frequently report a subjective slowing of the passage of time. However, experimental demonstrations of altered time perception in depressed patients are not conclusive. We added a timed action task (time-to-contact estimation, TTC) and compared this indirect time perception task to the more direct classical methods of verbal time estimation, time production, and time reproduction. In the TTC estimation task, the deviations of the estimates from the veridical values (relative errors) revealed no differences between depressed patients (n = 22) and healthy controls (n = 22). Neither did the relative errors of the TTC estimates differ between groups. There was a weak trend to…

Estándares SEA 2019 para el control global del riesgo cardiovascular

2019

One of the main goals of the Spanish Society of Arteriosclerosis is to contribute to a wider and greater knowledge of vascular disease, its prevention and treatment. Cardiovascular diseases are the leading cause of death in our country and also lead to a high degree of disability and health expenditure. Arteriosclerosis is a multifactorial disease, this is why its prevention requires a global approach that takes into account the different risk factors with which it is associated. Thus, this document summarizes the current level of knowledge and integrates recommendations and procedures to be followed for patients with established cardiovascular disease or high vascular risk. Specifically, t…

Mathematical modeling and parameters estimation of a car crash using data-based regressive model approach

2011

Author's version of an article in the journal: Applied Mathematical Modelling. Also available from the publisher at: http://dx.doi.org/10.1016/j.apm.2011.04.024 n this paper we present the application of regressive models to simulation of car-to-pole impacts. Three models were investigated: RARMAX, ARMAX and AR. Their suitability to estimate physical system parameters as well as to reproduce car kinematics was examined. It was found out that they not only estimate the one quantity which was used for their creation (car acceleration) but also describe the car's acceleration, velocity and crush. A virtual experiment was performed to obtain another set of data for use in further research. An A…

ModEst - Precise estimation of genome size from NGS data

2021

AbstractPrecise estimates of genome sizes are important parameters for both theoretical and practical biodiversity genomics. We present here a fast, easy-to-implement and precise method to estimate genome size from the number of bases sequenced and the mean sequence coverage. To estimate the latter, we take advantage of the fact that a precise estimation of the Poisson distribution parameter lambda is possible from truncated data, restricted to the part of the coverage distribution representing the true underlying distribution. With simulations we could show that reasonable genome size estimates can be gained even from low-coverage (10X), highly discontinuous genome drafts. Comparison of es…

noRANSAC for fundamental matrix estimation

2011

The estimation of the fundamental matrix from a set of corresponding points is a relevant topic in epipolar stereo geometry [10]. Due to the high amount of outliers between the matches, RANSAC-based approaches [7, 13, 29] have been used to obtain the fundamental matrix. In this paper two new contributes are presented: a new normalized epipolar error measure which takes into account the shape of the features used as matches [17] and a new strategy to compare fundamental matrices. The proposed error measure gives good results and it does not depend on the image scale. Moreover, the new evaluation strategy describes a valid tool to compare diffe rent RANSAC-based methods because it does not re…