Estimation of production consistency of diphtheria, tetanus, and pertussis components of the DTP vaccine using Shewhart charts

The Russian Federation puts special emphasis on vaccination-related issues, in accordance with the WHO recommendations. The fact that vaccination, in particular with the diphtheria, tetanus, and pertussis vaccine (DTP vaccine), covers large population groups, accounts for the relevance of research aimed at improving the quality of vaccines. One of the ways to produce vaccines of assured quality is to maintain consistent manufacturing processes that ensure consistency of product characteristics. The stability of the technological processes may be assessed using Shewhart charts. The aim of the study was to assess the production consistency of diphtheria, tetanus, and pertussis components of DTP vaccine using Shewhart control charts. Materials and methods: the study used data from 60 batch summary protocols of a Russian-produced DTP vaccine that were submitted to the Testing Centre of the Scientific Centre for Expert Evaluation of Medicinal Products from September 2017 until April 2020. The study assessed one of the main vaccine quality characteristics—specific (protective) activity of diphtheria, tetanus, and pertussis components. Shewhart charts for the diphtheria and tetanus components were constructed based on the manufacturer’s summary protocols, while Shewhart charts for the pertussis component were constructed based on both summary protocols and the results obtained by the Testing Centre during certification of the product batches. The Shewhart charts were used in accordance with the national standards GOST R 50779.42-99 and GOST R ISO 7870-2-2015. Results: a retrospective analysis of R- and X-charts covering a 2.5-year period revealed some characteristic trends in special-cause criteria. The most alarming situation was observed for the production of the diphtheria component. The technological processes were somewhat safer in the case of the tetanus and pertussis components. The production process lacked due statistical control, which is confirmed by the lack of correlation between the results of the pertussis component activity assessment obtained by the manufacturer and the Testing Centre. Conclusions: during the analysed period, the production of the diphtheria, tetanus, and pertussis components of the DTP vaccine was not always consistent. This highlights the need to conduct research aimed at standardisation of both production processes and control test conditions.

Understanding variation in reported covid-19 deaths with a novel Shewhart chart application

Objective Motivated by the coronavirus disease 2019 (covid-19) pandemic, we developed a novel Shewhart chart to visualize and learn from variation in reported deaths in an epidemic. Context Without a method to understand if a day-to-day variation in outcomes may be attributed to meaningful signals of change—rather than variability we would expect—care providers, improvement leaders, policy-makers, and the public will struggle to recognize if epidemic conditions are improving. Methods We developed a novel hybrid C-chart and I-chart to detect within a geographic area the start and end of exponential growth in reported deaths. Reported deaths were the unit of analysis owing to erratic reporting of cases from variability in local testing strategies. We used simulation and case studies to assess chart performance and define technical parameters. This approach also applies to other critical measures related to a pandemic when high-quality data are available. Conclusions The hybrid chart detected the start of exponential growth and identified early signals that the growth phase was ending. During a pandemic, timely reliable signals that an epidemic is waxing or waning may have mortal implications. This novel chart offers a practical tool, accessible to system leaders and frontline teams, to visualize and learn from daily reported deaths during an epidemic. Without Shewhart charts and, more broadly, a theory of variation in our epidemiological arsenal, we lack a scientific method for a real-time assessment of local conditions. Shewhart charts should become a standard method for learning from data in the context of a pandemic or epidemic.

Estimation of Consistency of Production of the Pertussis Component of DTP Vaccine in Terms of Immunogenic Activity and Specific Safety Using Shewhart Charts

WHO experts attribute the resurgence of whooping cough to the wide use of acellular pertussis vaccines (aPs) as components of combination products. In this regard, WHO encourages countries that have not yet switched to the use of aPs to continue to use whole-cell pertussis vaccines (wPs) for primary vaccination. The experience of using pertussis vaccines has shown that companies do not always produce highly efficacious products. The use of statistical methods of samples quality control helps to ensure consistency of the technological process, which results in the production of more homogeneous products, and rules out the possibility of producing low-quality products. This paper presents the results of retrospective evaluation of the consistency of the wP (as a pertussis component of the DTP vaccine) production using Shewhart control charts. It was shown that at some points in time during the analyzed period from January 2017 until March 2018 the technological process of the company lacked proper statistical control. This increased the risk of producing non-uniform and defective products. In order to improve the quality and consistency of pertussis component batches, the company’s quality control and quality assurance services should make extensive use of Shewhart charts on a real-time basis.

COMPARAÇÃO ENTRE GRÁFICOS DE CONTROLE DE SHEWHART, CUSUM E MMEP NO PROCESSO DE IRRIGAÇÃO POR ASPERSÃO CONVENCIONAL

COMPARAÇÃO ENTRE GRÁFICOS DE CONTROLE DE SHEWHART, CUSUM E MMEP NO PROCESSO DE IRRIGAÇÃO POR ASPERSÃO CONVENCIONAL JIAM PIRES FRIGO1; MARCIO ANTONIO VILAS BOAS2; JIANICE PIRES FRIGO2 E ELISANDRO PIRES FRIGO3 1 Instituto Latino-Americano de Tecnologia, Infraestrutura e Território - ILATIT (UNILA), Av. Tancredo Neves, 3838 - Porto Belo, CEP 85867-970, Foz do Iguaçu, PR, Fone (45)99993 4783, e‑mail:[email protected] Centro de Ciências Exatas e Tecnológicas, Programa de Pós Graduação em Engenharia Agrícola (Unioeste), R. Universitária, 2069 - Jardim Universitário CEP 85819-110, Cascavel-PR3 Universidade Federal do Paraná, Campus Palotina R. Pioneiro, 2153 - Dallas, CEP 85950-000, Palotina-PR 1 RESUMO O objetivo deste estudo foi comparar os resultados da utilização dos gráficos de controle de Shewhart para medidas individuais, com os gráficos de controle média móvel exponencialmente ponderada (MMEP) e soma cumulativa (CUSUM), aplicados no controle de qualidade da irrigação. Foram realizados 60 ensaios de irrigação em um sistema por aspersão convencional. As análises do processo de controle de qualidade do sistema de irrigação foram realizadas por meio dos gráficos de Shewhart (Xbarra), gráficos MMEP e CUSUM. Todos os procedimentos para os ensaios de uniformidade da irrigação foram realizados conforme recomendação NBR ISO 7749-2 (ABNT, 2000). Para a avaliação do sistema foi utilizado o Coeficiente de Uniformidade de Christiansen (CUC). O gráfico de controle MMEP apresentou-se bastante suscetível quando utilizado em dados auto correlacionados, com ocorrências de alarmes falsos. Para dados independentes (pelo modelo ARIMA), o gráfico CUSUM foi mais sensível ao detectar as variações ocorridas na irrigação devido à velocidade do vento, quando comparado aos gráficos MMEP e Shewhart para os mesmos dados. Na irrigação por aspersão, relacionando CUC com velocidade do vento, o gráfico de Shewhart foi mais indicado pela simplicidade, robustez e facilidade de interpretação, mesmo na presença de dados que violam a suposição de independência. Os gráficos de controle de Shewhart, MMEP e CUSUM provaram serem ótimas ferramentas estatísticas no estudo da irrigação por aspersão convencional, demonstrando muito bem a variabilidade no processo. Palavras-Chave: água, vento, Coeficiente de Christiansen, Controle de qualidade. FRIGO, J.P.; VILAS BOAS, M.A.; FRIGO, J.P.; FRIGO, E.P.COMPARISON BETWEEN SHEWHART CONTROL CHARTS, CUSUM AND MMEP IN PROCESS OF CONVENTIONAL IRRIGATION SPRINKLER 2 ABSTRACT This study aimed to compare the results of Shewhart control charts use for individual measures with exponentially weighted moving average (MMEP) and cumulative sum (CUSUM) control charts applied in quality control of conventional sprinkler irrigation. Sixty irrigation trials were set up in a conventional sprinkler system. The analyses of the quality control process of the irrigation system were performed by means of Shewhart charts (Xbarra) charts, MMEP and CUSUM. All procedures for testing uniformity of irrigation were performed as recommended by ISO 7749-2 (ABNT, 2000). For the evaluation of the system, it was used Christiansen Uniformity Coefficient (CUC). The control chart MMEP showed to be quite susceptible when used in auto correlated data with instances of false alarms. For independent data (the ARIMA model), the CUSUM tabular chart was more sensitive to detect variations in irrigation due to wind speed, when compared to MMEP and Shewhart charts for the same data. In sprinkler irrigation, relating CUC with wind speed, the Shewhart chart was better due to such features as simplicity, robustness and easiness of interpretation, even in the presence of data that violate the assumption of independence. The Shewhart control charts, CUSUM and MMEP statistics proved to be great tools in the study of irrigation sprinkler, demonstrating very well the variability in the process. Keywords: water, wind, Christiansen coefficient, control charts, Quality control.

Statistical Monitoring and Optimization of Electrochemical Machining using Shewhart Charts and Response Surface Methodology

The response surface methodology (RSM) and Shewhart control charts have been widely used in manufacturing to reduce variation, improve quality and optimize the output. This article proposes an application of individuals & moving range chart (I&MR) and RSM in electrochemical machining. The Shewhart-type I&MR control chart and RSM are combined together in an effective way to successfully guarantee the statistical control of the surface roughness (Ra) of the items produced by wire electrochemical turning, and meanwhile optimize Ra by exploring the optimal values of the machining parameters including applied voltage, wire feed rate, wire diameter, rotational speed and overlap distance. The conducted experiments reveal that the optimal values of the aforementioned factors are 23.67, 0.5, 0.2, 900 and 0.02, respectively. A second-order regression model is also developed to predict the output (Ra) at different combinations of the input parameters. The developed regression model can predict the output values with a determination coefficient (R2) of 96.9%. The proposed combined scheme of Shewhart charts and RSM can be employed in other manufacturing processes and even in different service sectors to efficiently enhance the performance and reduce the cost.

Use of statistical tools to assess the quality of education

The article discusses the problems associated with the management of the quality of education, it is shown that quality management education is impossible without reliance on proven statistical tools. The authors analyze the characteristics of quality management education and show that an integral element of the management of this process is the correct setting goals, having the operational and prediction properties in the zone of potential development of the student. The authors identify and justify the need for the provision of a system of indicators that allow determining the degree of achievement of objectives in the educational system. They analyze the classification of indicators from the point of view of education quality assessment identified a normative and comparative nature of the assessment indicators, the role and place of statistics in the evaluation of the quality of the educational process. Based on the conducted research the authors propose the method of using this statistical tool, as Shewhart charts, and to assess the implementation of the educational process and/or results and decision on the need for corrective actions. The article gives the definition of Shewhart charts, and describes the purpose of this instrument, marked the boundaries of its application, the analysis of varieties of charts, with the main features and the estimated values, the technique of their construction. Particular value is an example of using Shewhart charts to assess the quality of student performance, which demonstrates the role of this statistical tool in deciding the stability of the educational process or the need for corrective actions, i.e. external intervention in the process. The article may be interesting for practitioners in the course of training courses on the subject and in the process of improving quality management systems in educational institutions.