Search results for "standard deviation"
showing 10 items of 282 documents
Mass spectrometry strategies for mycotoxins analysis in European beers
2013
In this work, an existent solid-phase extraction (SPE) procedure was used to study the occurrence of mycotoxins in different European beers. HPLC-QqQ-MS/MS and ultra high resolution mass analyser have been optimized for the analysis of 18 mycotoxins: the methods were validated according to the EU Commission Decision 2002/657/EC guidelines. In this sense, matrix-matched calibration was performed for each type of beer, obtaining an effective quantification. The recoveries ranged from 63 to 91% and repeatability and reproducibility expressed as relative standard deviation (RSD%) were lower than 17%. On one hand, HPLC-LTQ-Orbitrap ® was used for unambiguous identification of target mycotoxins, …
I: Boxplots - die flexible Alternative zum „Antennenbildchen”
2002
Data description for continuous parameters is sometimes only based on means and standard deviations of measurement series, graphical representation only concentrates on corresponding "MSE plots", which provide means and standard deviations or even only mean squared errors. However, this strategy is only correct for normally distributed data. Outliers may seriously bias mean and standard deviations and may therefore lead to wrong clinical conclusions. The present paper suggests the use of medians and quartiles, which - just like their graphical pendant, the nonparametric "box whisker plot" - can be applied much more flexibly.
Employment effects of skills around the world: Evidence from the PIAAC
2020
Using an international survey that directly assesses the cognitive skills of participants, the author studies the effect of skills on employment in 32 countries. On average, a 1 standard deviation increase in numeracy is associated with an 8.4 percentage point increase in the probability of being employed, reducing the probability of being out of the labour force and unemployed by 6.4 and 2.1 percentage points, respectively. After controlling for numeracy, the estimated employment effect of years in education falls by one third, from 2.7 to 1.8 percentage points. Notably, the employment effect of skills is more pronounced in countries with higher unemployment.
Dimensional variability of nonstandardized greater taper finger spreaders with matching gutta-percha points
2001
Aim The purpose of this research was to determine the compatibility and dimensional variability between nonstandardized gutta-percha points and matching finger spreaders. Methodology The diameters of nonstandardized gutta-percha points (n = 15) and matching finger spreaders (n = 15) from different manufacturers (Kerr, Dentsply Maillefer, Vereignigte Dentalwerke and Roeko) were determined and statistically analysed using a profile projector under a magnification of 50 × (±0.002 mm). Results The dimensions of the finger spreaders and gutta-percha cones were inconsistent. Of the 29 groups of nonstandardized gutta-percha cones evaluated, 22 had standard deviations larger than 0.020 at D1. The s…
Observation of s-Channel Production of Single Top Quarks at the Tevatron
2014
We report the first observation of single-top-quark production in the s channel through the combination of the CDF and D0 measurements of the cross section in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV. The data correspond to total integrated luminosities of up to 9.7fb-1 per experiment. The measured cross section is σs=1.29-0.24+0.26pb. The probability of observing a statistical fluctuation of the background to a cross section of the observed size or larger is 1.8×10-10, corresponding to a significance of 6.3 standard deviations for the presence of an s-channel contribution to the production of single-top quarks. © 2014 American Physical Society.
Universal Organic Solvent−Water Partition Coefficient Model
1999
A method that permits a semiquantitative estimate of the partitioning of any solute between any two media is presented. As an example, the organic solvent-water partition coefficients P are calculated. Program GSCAP is written as a version of Pascal's SCAP program. The only needed parameters are the dielectric constant and molecular volume of the organic solvent. The log P results are compared with the Pomona database. The average absolute deviation is 1.48 log units and the standard deviation is 1.66 log units.
Benign — A typical nevi discrimination using diffuse reflectance and fluorescence multispectral imaging system
2015
Early diagnostics of skin cancer is of interest for dermatologists. Atypical nevi are not considered to be malignant, but are suspects that should be detected and monitored over time. The multispectral imaging system Nuance operating in spectral range 450–950 nm was adapted for clinical in vivo measurements in diffuse reflectance and fluorescence mode. Mean and standard deviation values of optical density and fluorescence intensity were extracted from segmented pigmented lesions (21 benign and 26 atypical nevi) and used for further analysis. It was possible to achieve 62% sensitivity and 67% specificity for discrimination between atypical and benign lesions using averaged fluorescence mean …
Prospective study of sport dropout: A motivational analysis as a function of age and gender
2012
Abstract Introduction: This paper aimed to analyse the predictive ability of a self-determination theory (SDT) based model describing competitive sport dropout, and variance as a function of age and gender. Variables included in the model were: psychological need satisfaction, self-determined motivation, perceived conflict between sport and study, intention to practise sport, and dropout. Methods: A prospective study was performed over a period of 19 months. Variables considered as predictors of sport dropout were measured initially, and after 19 months persistence or dropout was assessed. The sample consisted of 857 athletes aged 11–19 (mean value 15.3; standard deviation = 1.77), 680 male…
Observation of light-by-light scattering in ultraperipheral Pb+Pb collisions with the ATLAS detector
2019
This Letter describes the observation of the light-by-light scattering process, γγ→γγ, in Pb+Pb collisions at √sNN=5.02 TeV. The analysis is conducted using a data sample corresponding to an integrated luminosity of 1.73 nb−1, collected in November 2018 by the ATLAS experiment at the LHC. Light-by-light scattering candidates are selected in events with two photons produced exclusively, each with transverse energy EγT>3 GeV and pseudorapidity |ηγ|<2.4, diphoton invariant mass above 6 GeV, and small diphoton transverse momentum and acoplanarity. After applying all selection criteria, 59 candidate events are observed for a background expectation of 12±3 events. The observed excess of events…
APOGEE Data Releases 13 and 14: Stellar Parameter and Abundance Comparisons with Independent Analyses
2018
Data from the SDSS-IV / Apache Point Observatory Galactic Evolution Experiment (APOGEE-2) have been released as part of SDSS Data Releases 13 (DR13) and 14 (DR14). These include high resolution H-band spectra, radial velocities, and derived stellar parameters and abundances. DR13, released in August 2016, contained APOGEE data for roughly 150,000 stars, and DR14, released in August 2017, added about 110,000 more. Stellar parameters and abundances have been derived with an automated pipeline, the APOGEE Stellar Parameter and Chemical Abundance Pipeline (ASPCAP). We evaluate the performance of this pipeline by comparing the derived stellar parameters and abundances to those inferred from opti…