Dissertations / Theses on the topic 'Chemistry – Statistical methods'
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FREITAS, SONIA MARIA DE. "STATISTICAL METHODOLOGY FOR ANALYTICAL METHODS VALIDATION APPLICABLE CHEMISTRY METROLOGY." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2003. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=4058@1.
Full textA metodologia estatística escolhida para validação de métodos analíticos aplicável à metrologia em química é fundamental para assegurar a qualidade, comprovar a eficiência e demonstrar a exatidão dos resultados das medições nas análises químicas. Essa metodologia, desenvolvida em conformidade com o rigor metrológico, resulta num sistema de medições validado, confiável e com incertezas quantificadas. Este trabalho propõe uma metodologia geral para validação de métodos analíticos. A metodologia desenvolvida resultou de uma síntese de métodos parciais descritos na literatura, e inclui uma escolha crítica de técnicas mais adequadas dentro das alternativas existentes. A abordagem proposta combina quatro diferentes aspectos da validação: a modelagem da curva de calibração; o controle da especificidade do método; a comparação da tendência e precisão (repetitividade e precisão intermediária) do método com um método de referência; e a estimação das componentes de incerteza inerentes a todos esses aspectos. Como resultado, além de uma proposta para validação de métodos para uso em análises químicas, obtêm- se a função de calibração inversa e as incertezas expandidas, que permitem obter os resultados analíticos associados aos valores da resposta, com suas respectivas incertezas associadas. Na modelagem geral para obtenção da curva de calibração, empregam-se técnicas estatísticas para avaliação da linearidade e para o cálculo do mínimo valor detectável e do mínimo valor quantificável. A especificidade do método analítico é avaliada pela adição de padrões a um conjunto de amostras representativas e posterior recuperação dos mesmos, com ajuste por mínimos quadrados e testes de hipóteses. Para estudar a tendência e a precisão do método quando comparado a um método de referência, utiliza-se um modelo hierárquico de quatro níveis e a aproximação de Satterthwaite para determinação do número de graus de liberdade associados aos componentes de variância. As técnicas estatísticas utilizadas são ilustradas passo a passo por exemplos numéricos.
The use of statistical methodology for analytical methods validation is vital to assure that measurements have the quality level required by the goal to be attained. This thesis describes a statistical modelling approach for combining four different aspects of validation: checking the linearity of the calibration curve and compute the detection and the quantification limits; controlling the specificity of the analytical method; estimating the accuracy (trueness and precision) of the alternative method, for comparison with a reference method. The general approach is a synthesis of several partial techniques found in the literature, according to a choice of the most appropriate techniques in each case. For determination of the response function, statistical techniques are used for assessing the fitness of the regression model and for determination of the detection limit and the quantification limit. Method specificity is evaluated by adjusting a straight line between added and recovered concentrations via least squares regression and hypotheses tests on the slope and intercept. To compare a method B with a reference method A, the precision and accuracy of method B are estimated. A 4-factor nested design is employed for this purpose. The calculation of different variance estimates from the experimental data is carried out by ANOVA. The Satterthwaite approximation is used to determine the number of degrees of freedom associated with the variance components. The application of the methodology is thoroughly illustrated with step-by-step examples.
Farhat, Hikmat. "Studies in computational methods for statistical mechanics of fluids." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0026/NQ50157.pdf.
Full textAgrawala, Gautam Kumar. "Regional ground water interpretation using multivariate statistical methods." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2007. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
Full textGanti, Satyakala. "DEVELOPMENT OF HPLC METHODS FOR PHARMACEUTICALLY RELEVANT MOLECULES; METHOD TRANSFER TO UPLC: COMPARING METHODS STATISTICALLY FOR EQUIVALENCE." Diss., Temple University Libraries, 2011. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/118587.
Full textPh.D.
High Pressure Liquid Chromatography (HPLC) is a well-known and widely used analytical technique which is prevalent throughout the pharmaceutical industry as a research tool. Despite its prominence HPLC possesses some disadvantages, most notably slow analysis time and large consumption of organic solvents. Ultra Pressure Liquid Chromatography (UPLC) is a relatively new technique which offers the same separation capabilities of HPLC with the added benefits of reduced run time and lower solvent consumption. One of the key developments which facilitate the new UPLC technology is sub 2-µm particles used as column packing material. These particles allow for higher operating pressures and increased flow rates while still providing strong separation. Although UPLC technology has been available since early 2000, few laboratories have embraced the new technology as an alternative to HPLC. Besides the resistance to investing in new capital, another major roadblock is converting existing HPLC methodology to UPLC without disruption. This research provides a framework for converting existing HPLC methods to UPLC. An existing HPLC method for analysis of Galantamine hydrobromide was converted to UPLC and validated according to ICH guidelines. A series of statistical evaluations on the validation data were performed to prove the equivalency between the original HPLC and the new UPLC method. This research presents this novel statistical strategy which can be applied to any two methodologies to determine parity.
Temple University--Theses
Goodpaster, Aaron M. "Statistical Analysis Methods Development for Nuclear Magnetic Resonance and Liquid Chromatography/Mass Spectroscopy Based Metabonomics Research." Miami University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=miami1312317652.
Full textWoocay-Prieto, Arturo. "Groundwater hydrochemical facies, flowpaths and recharge determined by multivariate statistical, isotopic and chloride mass-balance methods." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2008. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
Full textGabrielsson, Jon. "Multivariate methods in tablet formulation." Doctoral thesis, Umeå : Univ, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-268.
Full textWang, Bo. "Novel statistical methods for evaluation of metabolic biomarkers applied to human cancer cell lines." Miami University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=miami1399046331.
Full textPham, Minh H. "Signal Detection of Adverse Drug Reaction using the Adverse Event Reporting System: Literature Review and Novel Methods." Scholar Commons, 2018. http://scholarcommons.usf.edu/etd/7218.
Full textMoller, Jurgen Johann. "The implementation of noise addition partial least squares." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/3362.
Full textWhen determining the chemical composition of a specimen, traditional laboratory techniques are often both expensive and time consuming. It is therefore preferable to employ more cost effective spectroscopic techniques such as near infrared (NIR). Traditionally, the calibration problem has been solved by means of multiple linear regression to specify the model between X and Y. Traditional regression techniques, however, quickly fail when using spectroscopic data, as the number of wavelengths can easily be several hundred, often exceeding the number of chemical samples. This scenario, together with the high level of collinearity between wavelengths, will necessarily lead to singularity problems when calculating the regression coefficients. Ways of dealing with the collinearity problem include principal component regression (PCR), ridge regression (RR) and PLS regression. Both PCR and RR require a significant amount of computation when the number of variables is large. PLS overcomes the collinearity problem in a similar way as PCR, by modelling both the chemical and spectral data as functions of common latent variables. The quality of the employed reference method greatly impacts the coefficients of the regression model and therefore, the quality of its predictions. With both X and Y subject to random error, the quality the predictions of Y will be reduced with an increase in the level of noise. Previously conducted research focussed mainly on the effects of noise in X. This paper focuses on a method proposed by Dardenne and Fernández Pierna, called Noise Addition Partial Least Squares (NAPLS) that attempts to deal with the problem of poor reference values. Some aspects of the theory behind PCR, PLS and model selection is discussed. This is then followed by a discussion of the NAPLS algorithm. Both PLS and NAPLS are implemented on various datasets that arise in practice, in order to determine cases where NAPLS will be beneficial over conventional PLS. For each dataset, specific attention is given to the analysis of outliers, influential values and the linearity between X and Y, using graphical techniques. Lastly, the performance of the NAPLS algorithm is evaluated for various
Wiklund, Susanne. "Spectroscopic data and multivariate analysis : tools to study genetic perturbations in poplar trees." Doctoral thesis, Umeå : Department of Chemistry, Umeå Univ, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1396.
Full textOosthuysen, Coenraad Willem. "Work management business process against employee engagement." Thesis, Stellenbosch : University of Stellenbosch, 2008. http://hdl.handle.net/10019.1/810.
Full textAFRIKAANSE OPSOMMING:‘n Kwalitatiewe evaluasie van die faktore wat werknemer verbintenis in die uitvoering van ‘n werksbestuur besigheidsproses beinvloed, word aangebied. Die nodigheid van werknemer verbintenis en besigheidsprosesse in organisasies word beskryf. ‘n Vergelyk tussen die beginsels van werknemer verbintenis en die werksbestuur proses word gedoen. Deur middel van statistiese evaluasie tegnieke (frekwensie evaluasie) dra hierdie navorsing by tot die bestaande kennis in hierdie domein deur die identifisering van faktore wat bydra tot die onttrekking van werknemers van die werksbestuur proses en gevolglik die organisasie verlaat. Resultate bevestig dat die werksbestuur proses die verbintenis van werknemers tot die werksbestuur proses fasiliteer, veral vir werknemers wat onlangs die arbeidsmark betree. Persoonlike groei en loopbaan ontwikkeling word egter nie ten volle ondersteun in die uitvoering van die werksbestuur proses nie. Aanbevelings word gemaak ter ondersteuning van die implementering van ‘n volhoubare werksbestuur proses.
ENGLISH ABSTRACT: Presents a qualitative evaluation of the factors that influence employee engagement from the perspective of implementing and sustaining a work management business process. Describes the intent of employee engagement and business processes in organizations. Compare the principles of employee engagement and the work management business process. By applying statistical evaluation methods (frequency analyses) this research adds to the existing body of knowledge in this field by identifying factors that lead to disengagement of employees in the execution of work management business processes and subsequent loss of skills. Analysis indicates that the business process facilitates engagement of employees in work management at the start of their careers, however career development and personal growth for experienced employees are lacking in the execution of work management. Concludes with recommendation for sustaining employee engagement in work management.
Chang, Qiang. "Continuous-time random-walk simulation of surface kinetics." The Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1166592142.
Full textBunch, Nathan. "Oral Fluid Method Validation for Bowling Green State University." Bowling Green State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1586969951770212.
Full textMehta, Darshan. "New Fragmentation Method to Enhance Structure-Based In Silico Modeling of Chemically-Induced Toxicity." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1449759891.
Full textLundberg, Robert. "Validation of Biomarkers for the Revision of the CEN/TR 15522-2:2012 Method : A Statistical Study of Sampling, Discriminating Powers and Weathering of new Biomarkers for Comparative Analysis of Lighter Oils." Thesis, Linköpings universitet, Kemi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-156975.
Full textSwann, Ellen Therese. "Development and application of statistical and quantum mechanical methods for modelling molecular ensembles." Phd thesis, 2018. http://hdl.handle.net/1885/142784.
Full textEbrahimi, Mohammadi Diako Chemistry Faculty of Science UNSW. "Multi-purpose multi-way data analysis." 2007. http://handle.unsw.edu.au/1959.4/40646.
Full textReichard, Eric Jonathan. "Chemometrics applied to the discrimination of synthetic fibers by microspectrophotometry." 2014. http://hdl.handle.net/1805/3795.
Full textMicrospectrophotometry is a quick, accurate, and reproducible method to compare colored fibers for forensic purposes. The use of chemometric techniques applied to spectroscopic data can provide valuable discriminatory information especially when looking at a complex dataset. Differentiating a group of samples by employing chemometric analysis increases the evidential value of fiber comparisons by decreasing the probability of false association. The aims of this research were to (1) evaluate the chemometric procedure on a data set consisting of blue acrylic fibers and (2) accurately discriminate between yellow polyester fibers with the same dye composition but different dye loadings along with introducing a multivariate calibration approach to determine the dye concentration of fibers. In the first study, background subtracted and normalized visible spectra from eleven blue acrylic exemplars dyed with varying compositions of dyes were discriminated from one another using agglomerative hierarchical clustering (AHC), principal component analysis (PCA), and discriminant analysis (DA). AHC and PCA results agreed showing similar spectra clustering close to one another. DA analysis indicated a total classification accuracy of approximately 93% with only two of the eleven exemplars confused with one another. This was expected because two exemplars consisted of the same dye compositions. An external validation of the data set was performed and showed consistent results, which validated the model produced from the training set. In the second study, background subtracted and normalized visible spectra from ten yellow polyester exemplars dyed with different concentrations of the same dye ranging from 0.1-3.5% (w/w), were analyzed by the same techniques. Three classes of fibers with a classification accuracy of approximately 96% were found representing low, medium, and high dye loadings. Exemplars with similar dye loadings were able to be readily discriminated in some cases based on a classification accuracy of 90% or higher and a receiver operating characteristic area under the curve score of 0.9 or greater. Calibration curves based upon a proximity matrix of dye loadings between 0.1-0.75% (w/w) were developed that provided better accuracy and precision to that of a traditional approach.
Wright, Eric Thomas. "Bayesian learning methods for potential energy parameter inference in coarse-grained models of atomistic systems." Thesis, 2015. http://hdl.handle.net/2152/30464.
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