Página 1 dos resultados de 8779 itens digitais encontrados em 0.026 segundos

Modifications for the tukey test procedure and evaluation of the power and efficiency of multiple comparison procedures; Modificações no procedimento para o teste de tukey e poder e eficiência de testes de comparações múltiplas

CONAGIN, Armando; BARBIN, Décio; DEMÉTRIO, Clarice Garcia Borges
Fonte: São Paulo - Escola Superior de Agricultura Luiz de Queiroz Publicador: São Paulo - Escola Superior de Agricultura Luiz de Queiroz
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
45.99%
Multiple pairwise comparison tests of treatment means are of great interest in applied research. Two modifications for the Tukey test were proposed. The power of unilateral and bilateral Student, Waller-Duncan, Duncan, SNK, REGWF, REGWQ, Tukey, Bonferroni, Sidak, unilateral Dunnet statistical tests and the modified tests, Sidak, Bonferroni 1 and 2, Tukey 1 and 2, has been compared using the Monte Carlo method. Data were generated for 600 experiments with eight treatments in a randomized block design, of which 400 had four and 200 eight blocks. The differences between the treatment means in relation to the control were 30%, 20%, 15%, 10%, 5%. Two extra treatments did not differ from the control. A coefficient of variation of 10% and a probability Type I error of α = 0.05 were adopted. The power of all the tests decreased when the differences to the control, decreased. The unilateral and bilateral Student t, Waller-Duncan and Duncan tests showed greater number of significative differences, followed by unilateral Dunnett, modified Sidak, modified Bonferroni 1 and 2, modified Tukey 1, SNK, REGWF, REGWQ, modified Tukey 2, Tukey, Sidak and Bonferroni. There is great loss of efficiency for all tests in relation to the unilateral Student t test for each difference of the treatment to the control...

Controle de qualidade no ajustamento de observações geodésicas

Klein, Ivandro
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
46.08%
Após o ajustamento de observações pelo método dos mínimos quadrados (MMQ) ter sido realizado, é possível a detecção e a identificação de erros não aleatórios nas observações, por meio de testes estatísticos. A teoria da confiabilidade faz uso de medidas adequadas para quantificar o menor erro detectável em uma observação, e a sua influência sobre os parâmetros ajustados, quando não detectado. A teoria de confiabilidade convencional foi desenvolvida para os procedimentos de teste convencionais, como o data snooping, que pressupõem que apenas uma observação está contaminada por erros grosseiros por vez. Recentemente foram desenvolvidas medidas de confiabilidade generalizadas, relativas a testes estatísticos que pressupõem a existência, simultânea, de múltiplas observações com erros (outliers). Outras abordagens para o controle de qualidade do ajustamento, alternativas a estes testes estatísticos, também foram propostas recentemente, como por exemplo, o método QUAD (Quasi-Accurate Detection of outliers method). Esta pesquisa tem por objetivo fazer um estudo sobre o controle de qualidade do ajustamento de observações geodésicas, por meio de experimentos em uma rede GPS (Global Positioning System)...

Modifications for the tukey test procedure and evaluation of the power and efficiency of multiple comparison procedures

Conagin,Armando; Barbin,Décio; Demétrio,Clarice Garcia Borges
Fonte: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz" Publicador: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz"
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2008 EN
Relevância na Pesquisa
45.99%
Multiple pairwise comparison tests of treatment means are of great interest in applied research. Two modifications for the Tukey test were proposed. The power of unilateral and bilateral Student, Waller-Duncan, Duncan, SNK, REGWF, REGWQ, Tukey, Bonferroni, Sidak, unilateral Dunnet statistical tests and the modified tests, Sidak, Bonferroni 1 and 2, Tukey 1 and 2, has been compared using the Monte Carlo method. Data were generated for 600 experiments with eight treatments in a randomized block design, of which 400 had four and 200 eight blocks. The differences between the treatment means in relation to the control were 30%, 20%, 15%, 10%, 5%. Two extra treatments did not differ from the control. A coefficient of variation of 10% and a probability Type I error of α = 0.05 were adopted. The power of all the tests decreased when the differences to the control, decreased. The unilateral and bilateral Student t, Waller-Duncan and Duncan tests showed greater number of significative differences, followed by unilateral Dunnett, modified Sidak, modified Bonferroni 1 and 2, modified Tukey 1, SNK, REGWF, REGWQ, modified Tukey 2, Tukey, Sidak and Bonferroni. There is great loss of efficiency for all tests in relation to the unilateral Student t test for each difference of the treatment to the control...

Two statistical tests for meiotic breakpoint analysis.

Plaetke, R; Schachtel, G A
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /02/1995 EN
Relevância na Pesquisa
46%
Meiotic breakpoint analysis (BPA), a statistical method for ordering genetic markers, is increasing in importance as a method for building genetic maps of human chromosomes. Although BPA does not provide estimates of genetic distances between markers, it efficiently locates new markers on already defined dense maps, when likelihood analysis becomes cumbersome or the sample size is small. However, until now no assessments of statistical significance have been available for evaluating the possibility that the results of a BPA were produced by chance. In this paper, we propose two statistical tests to determine whether the size of a sample and its genetic information content are sufficient to distinguish between "no linkage" and "linkage" of a marker mapped by BPA to a certain region. Both tests are exact and should be conducted after a BPA has assigned the marker to an interval on the map. Applications of the new tests are demonstrated by three examples: (1) a synthetic data set, (2) a data set of five markers on human chromosome 8p, and (3) a data set of four markers on human chromosome 17q.

Statistical Tests for Associations between Two Directed Acyclic Graphs

Hoehndorf, Robert; Ngonga Ngomo, Axel-Cyrille; Dannemann, Michael; Kelso, Janet
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 16/06/2010 EN
Relevância na Pesquisa
45.97%
Biological data, and particularly annotation data, are increasingly being represented in directed acyclic graphs (DAGs). However, while relevant biological information is implicit in the links between multiple domains, annotations from these different domains are usually represented in distinct, unconnected DAGs, making links between the domains represented difficult to determine. We develop a novel family of general statistical tests for the discovery of strong associations between two directed acyclic graphs. Our method takes the topology of the input graphs and the specificity and relevance of associations between nodes into consideration. We apply our method to the extraction of associations between biomedical ontologies in an extensive use-case. Through a manual and an automatic evaluation, we show that our tests discover biologically relevant relations. The suite of statistical tests we develop for this purpose is implemented and freely available for download.

Comparison of Statistical Tests for Disease Association with Rare Variants

Basu, Saonli; Pan, Wei
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.07%
In anticipation of the availability of next-generation sequencing data, there is increasing interest in investigating association between complex traits and rare variants (RVs). In contrast to association studies for common variants (CVs), due to the low frequencies of RVs, common wisdom suggests that existing statistical tests for CVs might not work, motivating the recent development of several new tests for analyzing RVs, most of which are based on the idea of pooling/collapsing RVs. However, there is a lack of evaluations of, and thus guidance on the use of, existing tests. Here we provide a comprehensive comparison of various statistical tests using simulated data. We consider both independent and correlated rare mutations, and representative tests for both CVs and RVs. As expected, if there are no or few non-causal (i.e. neutral or non-associated) RVs in a locus of interest while the effects of causal RVs on the trait are all (or mostly) in the same direction (i.e. either protective or deleterious, but not both), then the simple pooled association tests (without selecting RVs and their association directions) and a new test called kernel-based adaptive clustering (KBAC) perform similarly and are most powerful; KBAC is more robust than simple pooled association tests in the presence of non-causal RVs; however...

Rare-Variant Association Analysis: Study Designs and Statistical Tests

Lee, Seunggeung; Abecasis, Gonçalo R.; Boehnke, Michael; Lin, Xihong
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em 03/07/2014 EN
Relevância na Pesquisa
46.01%
Despite the extensive discovery of trait- and disease-associated common variants, much of the genetic contribution to complex traits remains unexplained. Rare variants can explain additional disease risk or trait variability. An increasing number of studies are underway to identify trait- and disease-associated rare variants. In this review, we provide an overview of statistical issues in rare-variant association studies with a focus on study designs and statistical tests. We present the design and analysis pipeline of rare-variant studies and review cost-effective sequencing designs and genotyping platforms. We compare various gene- or region-based association tests, including burden tests, variance-component tests, and combined omnibus tests, in terms of their assumptions and performance. Also discussed are the related topics of meta-analysis, population-stratification adjustment, genotype imputation, follow-up studies, and heritability due to rare variants. We provide guidelines for analysis and discuss some of the challenges inherent in these studies and future research directions.

Multivariate non-parametric statistical tests to reuse classifiers in recurring concept drifting environments

Gonçalves Júnior, Paulo Mauricio; Barros, Roberto Souto Maior de (orientador)
Fonte: Universidade Federal de Pernambuco Publicador: Universidade Federal de Pernambuco
Tipo: Dissertação
BR
Relevância na Pesquisa
56.08%
Data streams are a recent processing model where data arrive continuously, in large quantities, at high speeds, so that they must be processed on-line. Besides that, several private and public institutions store large amounts of data that also must be processed. Traditional batch classi ers are not well suited to handle huge amounts of data for basically two reasons. First, they usually read the available data several times until convergence, which is impractical in this scenario. Second, they imply that the context represented by data is stable in time, which may not be true. In fact, the context change is a common situation in data streams, and is named concept drift. This thesis presents rcd, a framework that o ers an alternative approach to handle data streams that su er from recurring concept drifts. It creates a new classi er to each context found and stores a sample of the data used to build it. When a new concept drift occurs, rcd compares the new context to old ones using a non-parametric multivariate statistical test to verify if both contexts come from the same distribution. If so, the corresponding classi er is reused. If not, a new classi er is generated and stored. Three kinds of tests were performed. One compares the rcd framework with several adaptive algorithms (among single and ensemble approaches) in arti cial and real data sets...

Multivariate non-parametric statistical tests to reuse classifiers in recurring concept drifting environments

Gonçalves Júnior, Paulo Mauricio
Fonte: Universidade Federal de Pernambuco Publicador: Universidade Federal de Pernambuco
Tipo: Tese de Doutorado
EN
Relevância na Pesquisa
56.08%
Data streams are a recent processing model where data arrive continuously, in large quantities, at high speeds, so that they must be processed on-line. Besides that, several private and public institutions store large amounts of data that also must be processed. Traditional batch classi ers are not well suited to handle huge amounts of data for basically two reasons. First, they usually read the available data several times until convergence, which is impractical in this scenario. Second, they imply that the context represented by data is stable in time, which may not be true. In fact, the context change is a common situation in data streams, and is named concept drift. This thesis presents rcd, a framework that o ers an alternative approach to handle data streams that su er from recurring concept drifts. It creates a new classi er to each context found and stores a sample of the data used to build it. When a new concept drift occurs, rcd compares the new context to old ones using a non-parametric multivariate statistical test to verify if both contexts come from the same distribution. If so, the corresponding classi er is reused. If not, a new classi er is generated and stored. Three kinds of tests were performed. One compares the rcd framework with several adaptive algorithms (among single and ensemble approaches) in arti cial and real data sets...

Statistical tests for the detection of single nucleotide polymorphisms using DNA pooling

Ramsey, David; Futschik, Andreas
Fonte: Internaitonal Statistical Institute Publicador: Internaitonal Statistical Institute
Tipo: info:eu-repo/semantics/conferenceObject; all_ul_research; ul_published_reviewed
ENG
Relevância na Pesquisa
55.87%
peer-reviewed; An important problem in genetics is detecting single nucleotide polymorphisms (SNPs), sites along the genome at which a population shows variation. The focus is on the detection of rare variants. Pooling individuals allows us to increase the probability that a rare variant appears in the sample. However, as the pool size increases, the mean number of reads from an individual decreases, making it harder to distinguish reads of a rare variant from errors. This paper compares three statistical tests for detecting SNPs using data from pooled DNA samples.

Time series motifs statistical significance

Castro, Nuno Constantino; Azevedo, Paulo J.
Fonte: SIAM Publicador: SIAM
Tipo: Conferência ou Objeto de Conferência
Publicado em //2011 ENG
Relevância na Pesquisa
46.04%
Time series motif discovery is the task of extracting previously unknown recurrent patterns from time series data. It is an important problem within applications that range from finance to health. Many algorithms have been proposed for the task of eficiently finding motifs. Surprisingly, most of these proposals do not focus on how to evaluate the discovered motifs. They are typically evaluated by human experts. This is unfeasible even for moderately sized datasets, since the number of discovered motifs tends to be prohibitively large. Statistical significance tests are widely used in bioinformatics and association rules mining communities to evaluate the extracted patterns. In this work we present an approach to calculate time series motifs statistical significance. Our proposal leverages work from the bioinformatics community by using a symbolic definition of time series motifs to derive each motif's p-value. We estimate the expected frequency of a motif by using Markov Chain models. The p-value is then assessed by comparing the actual frequency to the estimated one using statistical hypothesis tests. Our contribution gives means to the application of a powerful technique - statistical tests - to a time series setting.This provides researchers and practitioners with an important tool to evaluate automatically the degree of relevance of each extracted motif.

New Statistical Tests of Neutrality for DNA Samples from a Population

Fu, Y. X.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/1996 EN
Relevância na Pesquisa
46.07%
The purpose of this paper is to develop statistical tests of the neutral model of evolution against a class of alternative models with the common characteristic of having an excess of mutations that occurred a long time ago or a reduction of recent mutations compared to the neutral model. This class of population genetics models include models for structured populations, models with decreasing effective population size and models of selection and mutation balance. Four statistical tests were proposed in this paper for DNA samples from a population. Two of these tests, one new and another a modification of an existing test, are based on EWENS' sampling formula, and the other two new tests make use of the frequencies of mutations of various classes. Using simulated samples and regression analyses, the critical values of these tests can be computed from regression equations. This approach for computing the critical values of a test was found to be appropriate and quite effective. We examined the powers of these four tests using simulated samples from structured populations, populations with linearly decreasing sizes and models of selection and mutation balance and found that they are more powerful than existing statistical tests of the neutral model of evolution.

Exact Statistical Tests for Heterogeneity of Frequencies Based on Extreme Values

Wu, Chih-Chieh; Grimson, Roger C.; Shete, Sanjay
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em //2010 EN
Relevância na Pesquisa
46.03%
Sophisticated statistical analyses of incidence frequencies are often required for various epidemiologic and biomedical applications. Among the most commonly applied methods is Pearson's χ2 test, which is structured to detect non-specific anomalous patterns of frequencies and is useful for testing the significance for incidence heterogeneity. However, the Pearson's χ2 test is not efficient for assessing the significance of frequency in a particular cell (or class) to be attributed to chance alone. We recently developed statistical tests for detecting temporal anomalies of disease cases based on maximum and minimum frequencies; these tests are actually designed to test of significance for a particular high or low frequency. We show that our proposed methods are more sensitive and powerful for testing extreme cell counts than is the Pearson's χ2 test. We elucidated and illustrated the differences in sensitivity among our tests and the Pearson's χ2 test by analyzing a data set of Langerhans cell histiocytosis cases and its hypothetical sets. We also computed and compared the statistical power of these methods using various sets of cell numbers and alternative frequencies. Our study will provide investigators with useful guidelines for selecting the appropriate tests for their studies.

Bonferroni's and Sidak's modified tests

Conagin,Armando; Barbin,Décio
Fonte: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz" Publicador: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz"
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2006 EN
Relevância na Pesquisa
45.99%
Results of practical importance had been discarded testing formulated hypothesis with the aid of statistical analysis of experimental data because of the power of the utilized test. This study compares the power of two Bonferroni's Modified and one Sidak's Modified tests with known tests analyzing 1200 simulated experiments. All differences of means were obtained in relation to the mean of the adopted control to guarantee parametrical magnitude of mean differences. Student's test (type I comparisonwise error) and Waller-Duncan's (Bayesian error) showed the highest percentage of significative differences, followed by Duncan's, BM2, SiM, BM1, DunnettU's, SiN, BN, Dunnettu's, SNK's, REGWF's, REGWQ's, Tukey's, Sidak's and Bonferroni's tests. For differences equal to zero, Student's and Waller-Duncan's test exhibit 5% frequency of rejection of the null hypothesis, in accordance the nominal error I adopted (alpha = 0.05). All other tests had values below 0.05, generally ranging on 0.01 to 0.02 or less. Depending of the number of zero differences and considering the type I experimentwise error I, Student's, Waller-Duncan's and Duncan's tests showed crescent values of errors (> 0.05), proportional to the number of null differences included in the experiment; all other tests exhibit showed of type I experimentwise error < 0.05...

JavaNPST: Nonparametric Statistical Tests in Java

Derrac, J.; García, S.; Herrera, F.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 17/01/2015
Relevância na Pesquisa
46.05%
Nonparametric statistical tests are useful procedures that can be applied in a wide range of situations, such as testing randomness or goodness of fit, one-sample, two-sample and multiple-sample analysis, association between bivariate samples or count data analysis. Their use is often preferred to parametric tests due to the fact that they require less restrictive assumptions about the population sampled. In this work, JavaNPST, an open source Java library implementing 40 nonparametric statistical tests, is presented. It can be helpful for programmers and practitioners interested in performing nonparametric statistical analyses, providing a quick and easy way of running these tests directly within any Java code. Some examples of use are also shown, highlighting some of the more remarkable capabilities of the library.; Comment: 19 pages, 1 figure. Statistical Software Library for JAVA

Role of Statistical tests in Estimation of the Security of a New Encryption Algorithm

Krishna, Addepalli V. N; Babu, A Vinay
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 01/07/2010
Relevância na Pesquisa
46.01%
Encryption study basically deals with three levels of algorithms. The first algorithm deals with encryption mechanism, second deals with decryption Mechanism and the third discusses about the generation of keys and sub keys used in the encryption study. In the given study, a new algorithm is discussed. The algorithm executes a series of steps and generates a sequence. This sequence is being used as sub key to be mapped to plain text to generate cipher text. The strength of the encryption & Decryption process depends on the strength of sequence generated against crypto analysis.. In this part of work some statistical tests like Uniformity tests, Universal tests & Repetition tests are tried on the sequence generated to test the strength of it.; Comment: http://ijict.org/index.php/ijoat/article/view/statistical-tests-for-encryption-algorithm

Searching for non-gaussianity: Statistical tests

Forni, O.; Aghanim, N.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 11/05/1999
Relevância na Pesquisa
46.04%
Non-gaussianity represents the statistical signature of physical processes such as turbulence. It can also be used as a powerful tool to discriminate between competing cosmological scenarios. A canonical analysis of non-gaussianity is based on the study of the distribution of the signal in the real (or direct) space (e.g. brightness, temperature). This work presents an image processing method in which we propose statistical tests to indicate and quantify the non-gaussian nature of a signal. Our method is based on a wavelet analysis of a signal. Because the temperature or brightness distribution is a rather weak discriminator, the search for the statistical signature of non-gaussianity relies on the study of the coefficient distribution of an image in the wavelet decomposition basis which is much more sensitive. We develop two statistical tests for non-gaussianity. In order to test their reliability, we apply them to sets of test maps representing a combination of gaussian and non-gaussian signals. We deliberately choose a signal with a weak non-gaussian signature and we find that such a non-gaussian signature is easily detected using our statistical discriminators. In a second paper, we apply the tests in a cosmological context.; Comment: 14 pages...

Teste modificado de Bonferroni e Sidak; Bonferroni's and Sidak's modified tests

Conagin, Armando; Barbin, Décio
Fonte: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz Publicador: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; Formato: application/pdf
Publicado em 01/02/2006 ENG
Relevância na Pesquisa
45.99%
Results of practical importance had been discarded testing formulated hypothesis with the aid of statistical analysis of experimental data because of the power of the utilized test. This study compares the power of two Bonferroni's Modified and one Sidak's Modified tests with known tests analyzing 1200 simulated experiments. All differences of means were obtained in relation to the mean of the adopted control to guarantee parametrical magnitude of mean differences. Student's test (type I comparisonwise error) and Waller-Duncan's (Bayesian error) showed the highest percentage of significative differences, followed by Duncan's, BM2, SiM, BM1, DunnettU's, SiN, BN, Dunnettu's, SNK's, REGWF's, REGWQ's, Tukey's, Sidak's and Bonferroni's tests. For differences equal to zero, Student's and Waller-Duncan's test exhibit 5% frequency of rejection of the null hypothesis, in accordance the nominal error I adopted (alpha = 0.05). All other tests had values below 0.05, generally ranging on 0.01 to 0.02 or less. Depending of the number of zero differences and considering the type I experimentwise error I, Student's, Waller-Duncan's and Duncan's tests showed crescent values of errors (>; 0.05), proportional to the number of null differences included in the experiment; all other tests exhibit showed of type I experimentwise error < 0.05...

Modificações no procedimento para o teste de tukey e poder e eficiência de testes de comparações múltiplas; Modifications for the tukey test procedure and evaluation of the power and efficiency of multiple comparison procedures

Conagin, Armando; Barbin, Décio; Demétrio, Clarice Garcia Borges
Fonte: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz Publicador: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; Formato: application/pdf
Publicado em 01/01/2008 ENG
Relevância na Pesquisa
45.99%
Testes de comparações múltiplas entre médias de tratamentos são de grande interesse na pesquisa aplicada. Duas propostas de modificação do teste de Tukey são apresentadas e, usando-se simulação pelo método Monte Carlo, foi comparado o poder dos testes estatísticos: Student unilateral e bilateral, Waller-Duncan, Duncan, SNK, REGWF, REGWQ, Tukey, Bonferroni, Sidak, Dunnet unilateral, e dos testes modificados de Sidak, Bonferroni 1 e 2 e Tukey 1 e 2. Foram gerados dados para 600 experimentos em um delineamento casualizado em blocos com oito tratamentos, sendo 400 com quatro repetições e 200 com oito repetições. Foram adotados coeficiente de variação de 10% e erro tipo I com probabilidade α = 0.05. As diferenças entre as médias dos tratamentos e o controle foram de 30%, 20%, 15%, 10%, 5%; sendo, ainda incluídos, dois tratamentos que, parametricamente, não diferiram da média do controle. Para todos os testes, o poder decresceu quando as diferenças das médias em relação à média do controle decresceram; pela ordem, t de Student unilateral, t de Student bilateral e Waller-Duncan apresentaram maior número de diferenças significativas; seguindo-se Duncan, Dunnett unilateral, Sidak modificado e Bonferroni modificados 1 e 2 e Tukey modificado 1...

Application of discordancy and significance statistical tests for the comparison of dacitic volcanism from the central part of the Mexican Volcanic Belt

Díaz-González,Lorena; Cruz-Huicochea,René
Fonte: Universidad de La Salle Bajío A. C., Coordinación de Investigación Publicador: Universidad de La Salle Bajío A. C., Coordinación de Investigación
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2014 EN
Relevância na Pesquisa
56.06%
Our aim is to show a statistical procedure along with two new computer programs (DODESSYS and UDASYS). For this task we compiled a database of 249 samples of dacite coming from four closely located Mexican Volcanic Belt (MVB) areas: monogenetic volcanoes from the Sierra de Chichinautzin and Valle de México, the Nevado de Toluca stratovolcano, the Iztaccíhuatl stratovolcano and the Popocatépetl stratovolcano. The discordancy and significance (ANOVA -ANalysis Of Variance-, Fishers' F and Student's t) statistical tests were applied at 99% confidence level. The final statistical was calculated for 98 geochemical parameters, these include major oxides, rare earth elements, trace elements and additional parameters, as well as log-ratio parameters used in new tectonic discrimination diagrams. These geochemical parameters were treated as univariate statistical samples and were classified according with the four MVB regions. Discordancy statistical tests detected discordant outliers in 124 (amount to about 35%) statistical samples. ANOVA tests showed significant differences among all groups in 32 parameters. The similarities and differences between the log-ratios parameters elements may eventually be useful in future to propose tectonic discrimination diagrams from a representative database.