Search results for "regression"

Penalized logistic regression for small or sparse data: interval estimators revisited

2015

This paper focuses on interval estimation in logistic regression models fitted through the Firth penalized log-likelihood. In this context, many authors have claimed superiority of the Likelihood ratio statistic with respect to the (wrong) Wald statistic via simulation evidence. We re-assess such findings by detailing the inferential tools also including in the comparisons the (right) Wald statistic and other statistics neglected in previous literature. In particular, we assess performances of the CIs estimators by simulation and compare them in a real data set. Differently from previous findings, the Likelihood ratio statistic does not appear to be the best inferential device in Firth pena…

Quantifying Irrigated Winter Wheat LAI in Argentina Using Multiple Sentinel-1 Incidence Angles

2022

Synthetic aperture radar (SAR) data provides an appealing opportunity for all-weather day or night Earth surface monitoring. The European constellation Sentinel-1 (S1) consisting of S1-A and S1-B satellites offers a suitable revisit time and spatial resolution for the observation of croplands from space. The C-band radar backscatter is sensitive to vegetation structure changes and phenology as well as soil moisture and roughness. It also varies depending on the local incidence angle (LIA) of the SAR acquisition’s geometry. The LIA backscatter dependency could therefore be exploited to improve the retrieval of the crop biophysical variables. The availability of S1 radar time-series data at d…

Root cause analysis of large scale application testing results

2015

In this paper we present a new root cause analysis algorithm for discovering the most likely causes of the differences found in testing results of two versions of the same software. The problematic points in test and environment attribute hierarchies are presented to the user in compact way which in turn allows to save time on test result processing. We have proven that for clearly separated problem causes our algorithm gives exact solution. Practical application of described method is discussed.

MODEL DAN PELUANG TERJADINYA HUJAN BERDASARKAN KELEMBABAN MENGGUNAKAN REGRESI LOGISTIK BINER DI KABUPATEN MANOKWARI

2020

Manokwari Regrency has a tropical climate. This results in significant rainfall. One factor that stimulates rain is humidity. By using binary logistic regression, the model an chance of rainfall based on humidity can be determined. Logistic regression analysis is used to determine the relationship between categorical  scale response variables and numeric or categoric scale explanatory variables. If response variable used is nominal scale with  two possoble value (0 and 1), then it is called binary logistic regression. Estimation of the model  is done by logit  transformation. The model produce in this  study is g(x) = -23.443 + 0.289  humidity. The accuracy of the model is 70.4 percent and …

Generalized wavelets design using Kernel methods. Application to signal processing

2013

Abstract Multiresolution representations of data are powerful tools in signal processing. In Harten’s framework, multiresolution transforms are defined by predicting finer resolution levels of information from coarser ones using an operator, called the prediction operator, and defining details (or wavelet coefficients) that are the difference between the exact values and the predicted values. In this paper we present a multiresolution scheme using local polynomial regression theory in order to design a more accurate prediction operator. The stability of the scheme is proved and the order of the method is calculated. Finally, some results are presented comparing our method with the classical…

Meta-analysis of time perception and temporal processing in schizophrenia: Differential effects on precision and accuracy

2016

Numerous studies have reported that time perception and temporal processing are impaired in schizophrenia. In a meta-analytical review, we differentiate between time perception (judgments of time intervals) and basic temporal processing (e.g., judgments of temporal order) as well as between effects on accuracy (deviation of estimates from the veridical value) and precision (variability of judgments). In a meta-regression approach, we also included the specific tasks and the different time interval ranges as covariates. We considered 68 publications of the past 65years, and meta-analyzed data from 957 patients with schizophrenia and 1060 healthy control participants. Independent of tasks and…

An improvement of June-September rainfall forecasting in the Sahel based upon region April-May moist static energy content (1968-1997)

1999

This study provides statistical evidence that June–September Sahelian rainfall hindcasts currently based on oceanic thermal predictors apprehend more the negative trend than the interannual rainfall variations. Four physically meaningful predictors of June–September Sahel rainfall are first selected through the near-surface April–May information and several experimental hindcasts provided. We then discuss the skills achieved using regression techniques and cross-validated discriminant functions. In that context, 8/11 of the driest seasons and 8/10 of the wettest are correctly predicted. Finally using completely independent training and working periods we show that better and significant hin…

Associations between Finnish 9th grade students' school perceptions, health behaviors, and family factors

2012

PurposeThe aim of this study was to examine the associations between students' perceptions of the psychosocial school environment, health‐compromising behaviours, and selected family factors. The analyses were based on data provided for the Health Behaviour in School‐aged Children Study (2006).Design/methodology/approachThe data were obtained from 1,670 Finnish 9th graders. Logistic regression analysis was performed to identify the associations between school perceptions, health‐compromising behaviours, and selected family factors.FindingsEducational aspiration was found to be the most influential factor connected to health‐compromising behaviour among both genders, favouring students who w…

2020

Introduction/Purpose: Physical activity and sedentary time may associate with physical fitness and body composition. Yet, there exists some observational studies that have investigated the associations of device-based measures of sedentary time and physical activity (PA) with cardiorespiratory fitness (CRF) and body composition but associations with muscular fitness (MF) are less studied.Methods: Objective sedentary time and physical activity was measured by a hip worn accelerometer from 415 young adult men (age: mean 26, standard deviation 7 years). Cardiorespiratory fitness (VO2max) (CRF) was determined using a graded cycle ergometer test until exhaustion. Maximal force of lower extremiti…

Gender Differences In Stem Courses: Analysis Of Italian Students' Performance

2021

Gender gap in Science, Technology, Engineering and Mathematics (STEM) courses is a prevalent topic in the recent literature, and quantitative studies on this relationship are essential to understand better the discussion and issues claimed by the arguments and the theories on this topic. In Italy, since 1989, the overall share of females enrolling at university is larger than the males' one, but females are still underrepresented in almost all the STEM fields, while overrepresented in nursing, humanities, and law schools. Our paper aims to investigate the gender differences in terms of university performance in STEM courses in Italy. This is done via segmented regression models, representin…