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Matemática e Estatística / Mathematics and Statistics

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Browsing Matemática e Estatística / Mathematics and Statistics by Sustainable Development Goals (SDG) "12:Produção e Consumo Sustentáveis"

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  • The Mixed CUSUM-EWMA (MCE) control chart as a new alternative in the monitoring of a manufacturing process
    Publication . Oliveira, Amilcar; Oliveira, Teresa A.; Paladini, Edson Pacheco; Walter, Olga Maria Formigoni Carvalho; Henning, Elisa; Konrath, Andréa Cristina; Alves, Custodio da Cunha
    Goal: The objective is to conclude, based on a comparative study, if there is a significant difference in sensitivity between the application of MCE and the individual application of the CUSUM or EWMA chart, i.e., greater sensitivity particularly for cases of lesser magnitude of change. Design/Methodology/Approach: These are an applied research and statistical techniques such as statistical control charts are used for monitoring variability. Results: The results show that the MCE chart signals a process out of statistical control, while individual EWMA and CUSUM charts does not detect any situation out of statistical control for the data analyzed. Limitations: This article is dedicated to measurable variables and individual analysis of quality characteristics, without investing in attribute variables. The MCE chart was applied to items that are essential to the productive process development being analysed. Practical Implications: The practical implications of this study can contribute to: the correct choice of more sensitive control charts to detect mainly small changes in the location (mean) of processes; provide clear and accurate information about the fundamental procedures for the implementation of statistical quality control; and encourage the use of this quality improvement tool. Originality/Value: The MCE control chart is a great differential for the improvement of the quality process of the studied company because it goes beyond what CUSUM and EWMA control charts can identify in terms of variability.
    2019-01-21Journal article Restricted access Show more
  • Uncovering abnormal water consumption patterns for sustainability’s sake: a statistical approach
    Publication . Borges, Ana; Cordeiro, Clara; Ramos, Maria do Rosário
    Monitoring domestic water usage may help the water utilities uncover abnormal water consumption. In this context, it is necessary to improve and develop tools based on data analysis of households’ meter readings. This study contributes to this goal by using a statistical methodology that detects abnormal water consumption patterns, namely, significant increases or decreases. This approach relies on a combination of methods that analyse billed water consumption time series. The first step is to decompose the time series using Seasonal-Trend decomposition based on Loess. Next, breakpoint analysis is performed on the seasonally adjusted time series to look for changes in the pattern over time. Afterwards, the Mann–Kendall test and Sen’s slope estimator are applied to assess whether there are significant increases or decreases in water consumption. The strategy is applied to water consumption data from the Algarve, Portugal, successfully detecting breakpoints associated with significant increasing or decreasing trends.
    2022-11-29Conference object Restricted access Show more