Evaluation of nine USGS reference materials for quality control through Univariate Data Analysis System, UDASys3

Rosales-Rivera, Mauricio; Díaz-González, Lorena; Verma, Surendra P.

doi:10.1007/s12517-018-4220-0

Cited by 15 publications

(14 citation statements)

References 27 publications

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“…The presence of outliers in geochemical data can impact the accuracy of the interpretation, and considering the possible reasons is therefore an important consideration before going for any meaningful interpretations (Verma, , ). This is more relavent when there are several data points marked as outliers (Rosales‐Rivera, Díaz‐González, & Verma, ). Sometimes the outliers may be the indicators of a different climatic episodes (Pandarinath, ).…”

Section: Sampling and Analytical Methodsmentioning

confidence: 99%

“…Sometimes the outliers may be the indicators of a different climatic episodes (Pandarinath, ). The chemical composition data for the 27 surface acid rocks were analysed for outliers by applying the computer programme UDASys3.2 (Rosales‐Rivera et al, ). Several data points for the major element oxides, REE and the trace elements in various acid rocks were identified as outliers (Table S1).…”

Section: Sampling and Analytical Methodsmentioning

confidence: 99%

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Mineralogical and geochemical changes due to hydrothermal alteration of the volcanic rocks at Acoculco geothermal system, Mexico

et al. 2020

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Most of the volcanic rocks in the Acoculco geothermal system (AGS), near to the surface manifestations, are intensively altered. Thirty‐four surface volcanic rocks and five rocks from outcrop sections are considered in this work. Silica polymorphs (quartz, cristobalite and tridymite) are the dominant hydrothermal minerals in almost all the rock samples. The following other minerals are present in minor concentrations: alkali‐feldspars (sanidine potassic, anorthoclase and microcline), plagioclase feldspars (albite and anorthite), clay minerals (illite, kaolinite and montmorillonite), anhydrite, buddingtonite, titanoaugite, magnetite and anatase. This type of mineral assemblage of the rocks indicates an intensive silicic and argillic alteration. Comparison of the elemental concentrations of the surface acid rocks of the AGS with that of the precursor rock has indicated alteration‐induced changes in (a) chemical mobility in the concentrations of major element oxides, with an increase in the concentrations of SiO2, and TiO2, loss in those of Al2O3, Fe2O3, MnO, MgO, CaO, Na2O and K2O, and no statistically significant changes in those of P2O5, (b) no significant changes in the concentrations of LREE and MREE (except Dy and Ho), however, less but significant loss in the concentrations of Dy and Ho, and HREE, and (c) there is an enrichment in the concentrations of Nd, Sr, Sc, V, Nb, Ag, Sn, Pb, Tl, Ta, U and Th; and depletion in Be, Co, Zn, Ga, Ge, Rb, Y, Zr, Mo, Cs, Ba and Hf compared to those of the precursor rock. This type of distribution of the elements may indicate (a) an intense silicic alteration; and (b) REEs might have been leached from the original rocks because of hydrothermal alteration processes, but only LREEs, and MREEs (except Dy and Ho) can be redistributed and accommodated in the hydrothermal minerals, providing them with somewhat inert (immobile) behaviour. The mass change calculations have indicated that MnO and Sr have experienced the greatest and smallest mass changes, respectively. The identification of outliers in chemical data has revealed the presence of two distinctive groups of rocks. Ten out of the total 27 acid volcanic rocks with several elements as outlier data are negligibly to moderately altered (Group‐1), and the remaining 17 acid rocks without outlier data are intensively altered rocks (Group‐2).

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Section: Sampling and Analytical Methodsmentioning

confidence: 99%

Section: Sampling and Analytical Methodsmentioning

confidence: 99%

Mineralogical and geochemical changes due to hydrothermal alteration of the volcanic rocks at Acoculco geothermal system, Mexico

et al. 2020

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“…Both versions of a computer program UDASys (UDASys2 34 and UDASys3 35 ) apply recursive tests 41-43 with prior application of single-outlier discordancy tests, 29, 44, 45 all with new, precise, and accurate critical values. 34, 35, 46-49 The application of significance tests (F, t , and ANOVA) also requires the normality of the statistical samples, which can be achieved through discordancy tests from any of the 2 versions of UDASys, prior to the inference about similarities or differences between or among statistical samples. Thus, the discordancy tests can be applied to samples of sizes as large as 30,000 and significance tests to the number of sample groups as large as 30.…”

Section: Recent Advances In Statistical Handling Of Datamentioning

confidence: 99%

“…The main deficiency concerning the statistical treatment of these data seems to be the lack of application of modern discordancy tests 29-37 in the handling of univariate, bivariate, or multivariate data, because no commercial software is available for this purpose. However, appropriate software, such as UDASys2 (Univariate Data Analysis System version 2), 34 UDASys3 (Univariate Data Analysis System version 3), 35 BIDASys (Bivariate Data Analysis System), 36 and DOMuDaF (Discordant Outliers from Multivariate Data from the F test of w), 37 have been recently developed and published to facilitate these applications.…”

Section: Introductionmentioning

confidence: 99%

“…Not only the mean and standard deviation values are affected by the presence of discordant outliers but also the so-called robust parameters such as the median, including the percentiles, are prone to them. 34, 35, 38-40 In one study, 11 outlying observations were identified but not from the modern tests based on new precise and accurate critical values and those having the best performance (highest power of test and lowest masking and swamping effects). 29, 33-40…”

Section: Introductionmentioning

confidence: 99%

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Statistical Methodology for Medical Data: Gestational Age, Birth Weight, and Hand Characteristics

Verma

Sharma

2018

Journal of Neonatology

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We briefly review the current trend in handling the neonatal baby weight, gestational age, and other related categorical and continuous variable data, through both robust and outlier-based methods. Graphs are generally presented as smooth curves which give a wrong visual impression and totally hide the actual variability of the data, robust methods are applied without considering that they may certainly be affected by asymmetrical contamination, and the outlier-based methods are incorrectly applied without ascertaining if the individual data arrays are normally distributed, free from discordant observations. Aim: To demonstrate our new procedure for handling of neonatal baby data from two case studies. Methodology: The univariate data were handled through the application of discordancy tests in the light of new precise and accurate critical values, and significance tests were applied to both original and discordant outlier-free data arrays. The bivariate data were also handled from identifying and separating discordant outliers and reporting the quality of the coefficients in terms of standard errors. Finally, the supervised multivariate technique of linear discriminant and canonical analysis is successfully applied. Results: The results of significance tests for some cases varied from the use of all data versus censored data. The identification and separation of bivariate discordant outliers drastically improved the quality of regression lines. Linear discriminant and canonical analysis provided high success values for laboratory-controlled experiments. Conclusion: The need of obtaining both central tendency and dispersion parameters in all medical data is established. The reporting of regression coefficients with individual errors is recommended.

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Geochemistry, petrogenesis, and tectonic setting of the Los Tuxtlas Volcanic Field, Mexico

et al. 2020

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We present new major and trace element geochemical data, including the rare‐earth elements (REE), platinum group elements and Au, and combine them with the published information to constrain the highly debated origin of magmas in the Los Tuxtlas Volcanic Field (LTVF) of the Late Miocene to historic age. The LTVF magmas originated in the garnet‐bearing mantle as confirmed from the partial melting models of the REE. The mantle‐derived magmas may have subsequently undergone fractional crystallization of mainly olivine. The controversial tectonic setting of the LTVF was solved by log‐ratio transformed major as well as combined major and trace element data as a continental strike‐slip fault setting during the Miocene–Pliocene. During the Pleistocene to Holocene, the more numerous samples having only major elements alone indicated the continental strike‐slip fault setting, whereas the lesser number of samples having combined major and trace elements were more consistent with the continental extension. Importantly, no geochemical evidence for the involvement of the subducting slab in the magma genesis of the LTVF could be inferred. The inferences presented in this work were consistent with the entirety of geological, geochemical, and geophysical evidence. The multidimensional models also showed that the monogenetic volcanic field of the Xalapa region of the easternmost part of the Mexican Volcanic Belt represents a continental extension setting.

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Evaluation of nine USGS reference materials for quality control through Univariate Data Analysis System, UDASys3

Cited by 15 publications

References 27 publications

Mineralogical and geochemical changes due to hydrothermal alteration of the volcanic rocks at Acoculco geothermal system, Mexico

Mineralogical and geochemical changes due to hydrothermal alteration of the volcanic rocks at Acoculco geothermal system, Mexico

Statistical Methodology for Medical Data: Gestational Age, Birth Weight, and Hand Characteristics

Geochemistry, petrogenesis, and tectonic setting of the Los Tuxtlas Volcanic Field, Mexico

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