Search results for "STATISTICS"
showing 10 items of 7671 documents
Behaviour of common estimators in dynamic error-components models with autocorrelated disturbances
1997
The purpose of this paper is to make a presentation of the properties of a set of estimators comprising the within, between, OLS and GLS estimators in the study of dynamic error - components models with autocorrelated disturbances. We underline in this study the importance of the statistical distribution governing the initial values for the process and the structure of xit variable for the limiting values of the estimators when the temporal dimension is fixed but the individual dimension N grows indefinitly.
Accuracy and Reliability of Cone-Beam Computed Tomography for Linear and Volumetric Mandibular Condyle Measurements. A Human Cadaver Study
2017
AbstractThe accuracy of Cone-Beam Computed Tomography (CBCT) on linear and volumetric measurements on condyles has only been assessed on dry skulls. The aim of this study was to evaluate the reliability and accuracy of linear and volumetric measurements of mandibular condyles in the presence of soft tissues using CBCT. Six embalmed cadaver heads were used. CBCT scans were taken, followed by the extraction of the condyles. The water displacement technique was used to calculate the volumes of the condyles and three linear measurements were made using a digital caliper, these measurements serving as the gold standard. Surface models of the condyles were obtained using a 3D scanner, and superim…
Perceived statistical knowledge level and self-reported statistical practice among academic psychologists
2018
Introduction: Publications arguing against the null hypothesis significance testing (NHST) procedure and in favor of good statistical practices have increased. The most frequently mentioned alternatives to NHST are effect size statistics (ES), confidence intervals (CIs), and meta-analyses. A recent survey conducted in Spain found that academic psychologists have poor knowledge about effect size statistics, confidence intervals, and graphic displays for meta-analyses, which might lead to a misinterpretation of the results. In addition, it also found that, although the use of ES is becoming generalized, the same thing is not true for CIs. Finally, academics with greater knowledge about ES sta…
CATs: whither and whence
2000
TAI: Hacia dónde y de dónde. En este trabajo esbozo el estado de la
 cuestión que dio lugar a los test adaptativos, centrando la discusión en el
 avance de los TAI y en particular en las expectativas que expresara Bert
 Green sobre las ventajas de esta tecnología. Se usan datos de la primera
 década donde los TAI fueron operativos, para comparar lo que ocurrió con
 aquello que se esperaba que ocurriera. Encuentro que algunas de las metas
 de TAI expresadas por Green están próximas a cumplirse, aunque la
 mayoría de ellas quedan para el futuro.
Qualitative analysis by experts of the essential elements of the nursing practice environments proposed by the TOP10 questionnaire of assessment of e…
2020
Background: A short TOP10 scale based on the Practice Environment Scale-Nursing Work Index questionnaire measures the characteristics of nursing work environments. Positive environments result in better quality care and health outcomes. Objective: To identify a small number of core elements that would facilitate more effective interventions by nurse managers, and compare them with the essential elements proposed by the TOP10. Method: Qualitative research by a nominal group of eight experts. The content analysis was combined with descriptive data. Results: Ten most important items were selected and analyzed by the expert group. A high level of consensus in four items (2, 15, 20, 31) and an a…
Assessing farming eco-efficiency: a Data Envelopment Analysis approach.
2010
This paper assesses farming eco-efficiency using Data Envelopment Analysis (DEA) techniques. Eco-efficiency scores at both farm and environmental pressure-specific levels are computed for a sample of Spanish farmers operating in the rain-fed agricultural system of Campos County. The determinants of eco-efficiency are then studied using truncated regression and bootstrapping techniques. We contribute to previous literature in this field of research by including information on slacks in the assessment of the potential environmental pressure reductions in a DEA framework. Our results reveal that farmers are quite eco-inefficient, with very few differences emerging among specific environmental …
The Reprocessed Proba-V Collection 2: Product Validation
2021
With the objective to improve data quality in terms of cloud detection, absolute radiometric calibration and atmospheric correction, the PRoject for On-Board Autonomy-Vegetation (PROBA-V) data archive (October 2013 - June 2020) will be reprocessed to Collection 2 (C2). The product validation is organized in three phases and focuses on the intercomparison with PROBA-V Collection 1 (C1), but also consistency analysis with SPOT-VGT, Sentinel-3 SYN-VGT, Terra-MODIS and METOP-AVHRR is foreseen. First preliminary results show the better performance of cloud and snow/ice masking, and indicate that statistical consistency between PROBA-V C2 and C1 are in line with expectations. PROBA-V C2 data are …
Prototype for Surface Albedo Retrieval Based on Sentinel-3 OLCI and SLSTR Data in the Framework of Copernicus Climate Change
2021
This work describes the different algorithmic steps used to retrieve the first Surface Albedo (SA) product based on Sentinel-3 (S-3) data in the framework of the Copernicus Climate Change Service (C3S). The atmospherically corrected Top-Of-Atmosphere (TOA) reflectances into Top-Of-Canopy (TOC) reflectances are brokered from the Copernicus Global Land Service (CGLS). The TOC reflectances are used to obtain a BRDF model. Next, the spectral and angular integration steps are implemented, which take the latter coefficients as input to produce spectral and broadband albedo quantities. The preliminary quality assessment of BSA broadband albedo for the total shortwave shows good overall spatiotempo…
Spike train statistics for consonant and dissonant musical accords in a simple auditory sensory model
2010
The phenomena of dissonance and consonance in a simple auditory sensory model composed of three neurons are considered. Two of them, here so-called sensory neurons, are driven by noise and subthreshold periodic signals with different ratio of frequencies, and its outputs plus noise are applied synaptically to a third neuron, so-called interneuron. We present a theoretical analysis with a probabilistic approach to investigate the interspike intervals statistics of the spike train generated by the interneuron. We find that tones with frequency ratios that are considered consonant by musicians produce at the third neuron inter-firing intervals statistics densities that are very distinctive fro…
Flexible Estimation of Heteroskedastic Stochastic Frontier Models via Two-step Iterative Nonlinear Least Squares
2019
Despite its importance, the monotonicity condition is typically overlooked in stochastic frontier analysis. This article illustrates a straightforward and useful method for the estimation of semiparametric stochastic frontier models imposing such constraint and incorporating exogenous inefficiency effects exploiting the scaling property. An iterative estimation algorithm based on nonlinear least squares is developed and the behavior of the proposed procedure is investigated through a set of Monte Carlo experiments comparing its finite sample properties with those of available alternatives. The simulation results highlight very good performance of the new algorithm which outperforms the comp…