Lean Sigma Research Articles

Statistical Test of Two Taguchi Six-Sigma Quality Indices to Select the Supplier with Optimal Processing Quality

Abstract Because of rapid changes in consumer needs, diverse and small-batch production has become a crucial strategy for companies progressing toward sustainability in intensely competitive industries. To swiftly meet the diverse needs of consumers using this production strategy, often manufacturers must outsource noncore processes to external contractors or purchase component parts from suppliers. The objective of this article was to develop a supplier selection model based on the processing quality of suppliers. Owing to the fact that the Taguchi Six-Sigma quality index for process with nominal-the-best specification (Qpm) can fully reflect product loss and the achieved quality level for the quality characteristic of the process in question, Qpm is employed as a tool to assess and compare the processing quality level of two-sided specification limits provided by each supplier. In practice, Qpm is based on the sample data collected from a stable process to estimate prior to the processing quality assessment. This can lead to misjudgment because of sampling error. To increase the reliability of supplier selection, we further propose hypothesis testing of the quality index Qpm for two suppliers. The applicability and effectiveness of the proposed model is validated using an example involving the double-sided grinding process of a bicycle disc brake.

Global study into the pros and cons of ISO 18404: a convergent mixed method study and recommendations for further research

PurposeThe paper aims to investigate the pros and cons of having a standard for lean six sigma developed in 2015. The study follows up on a previous study by Antony et al. (2021) in more depth and aims to provide a more detailed investigation of various aspects of the standard.Design/methodology/approachA sequential mixed methodology was utilised by interviewing a panel of leading academics and practitioners familiar with lean six sigma followed by distributing a survey questionnaire to continuous improvement and operational excellence (OPEX) personnel.FindingsThe findings indicate that continuous improvement and OPEX professionals have conflicting views of International Standards Organisation (ISO) 18404. A majority of the participants of the qualitative study suggested, whilst supporting the requirement for a lean sigma standard, voiced concerns about the auditability of the standard and whether it is currently “fit for purpose” and proposed that it needs to be revised. Within the quantitative survey, 42% had never heard of the standard, and of the 58% who had heard of it, 90% had read it. Just 10% stated that they had or would apply the standard within their organisations. Just fewer than 50% felt that the standard was fit for purpose which suggests for further refinements of the standard in the future. Finally, 85% of respondents of the quantitative survey suggested for the revision of the standard whilst just 15% felt it should be removed.Research limitations/implicationsOther than a previous study by Antony et al. (2021), implementation of ISO 18404 in organisations and its benefits as well as empirical study looking into the impact of the standard on corporate performance in the literature were limited. An opportunity to review lessons learnt from a case study on the ISO 18404 standard implementation within an organisation would further enhance the research.Originality/valueThe paper provides a valuable resource for organisations to obtain insight into a standard in lean six sigma and whether to implement it or not. Furthermore, the results can form the basis of a case for the future revision of the standard by consolidating and strengthening the findings from the first study with more detailed quantitative and qualitative study.

The Impact of Continuous Improvement Concepts on the Performance of Furniture Production Processes

Most small and medium-sized enterprises in the furniture industry use simple partial approaches to improve or manage production processes. The article aims to present research results focused on continuous process improvement through the implementation of Six Sigma (SS) and Lean Six Sigma (LSS) concepts in furniture production. Their impact on the performance via the level of the ROE (Return on Equity) indicator was evaluated using statistical methods of Chi-square test and Cramer’s contingency coefficient. The results of the research showed that furniture enterprises that had implemented selected methods of quality management reached a medium level of ROE values. The absence of a more comprehensive approach to managing the performance of processes was the impulse for a model creation based on the interconnection of SS and LSS concepts. The model should a practical use of appropriate methodologies and procedures in the management of furniture production processes, as well as in their optimisation. A thorough analysis of non-conforming products performed in furniture manufacturing processes transformed into SS and LSS metrics and the implementation of the model in the enterprise led to reduced process waste by reducing the number of non-conforming products, reducing the cost of such products, and increasing the capability of critical processes. Implications for Central European audience: The combination of theoretical knowledge in performance management and quality of production processes and practical knowledge from the real implementation of methods and tools for continuous improvement of production process capability in the company proved to be a good basis for creating a model within SS and LSS. These facts have contributed to the development of scientific knowledge. The presented application of methods and tools within SS and LSS will provide instructions for the use of new management methods. The specific outputs of the research work improve defining problems, measuring process parameters, analysis of measured data, improving furniture production processes.

Six Sigma Approach to Enhance Concurrency of the Procurement Process for Raw Materials

This paper presents the improvement of the procurement process for raw materials in a real manufacturing company supported by the Lean Sig Sigma as structured approach to deliver the improvement. The manufacturing company that is a subject of this paper have received a significant amount of complains regarding the internal purchase orders approval process and the overall procurement process of the company from both internal employees and external vendors and contractors. Considering that the company is procuring the raw goods from selected vendors, therefore the entire manufacturing plan depends on these materials, the company decided to improve this process trough Lean Six Sigma. The Lean Six Sigma approach was selected in order to obtain the improvement in a short time, based on indicators that were previously analyzed and prioritized. The paper focuses on simplifying of the process trough decreasing the number of mandatory steps.

An evaluation of Lean and Six Sigma methodologies in the national health service

PurposeThe purpose of this paper is to conduct an empirical study derived from the previous literature from the perspective of benefits, tools and techniques, continuous improvement (CI) and quality improvement (QI) methodologies and critical failure factors (CFFs) of Lean and Six Sigma (SS) in the national health service (NHS).Design/methodology/approachA literature review was carried out to identify previous findings, empirical data and critical variables concerning Lean and SS in healthcare for over ten years. Second, primary research in quantitative surveys and qualitative interviews was carried out with 110 participants who have experience using Lean and SS in the NHS.FindingsLean and SS have evolved into common practices within the NHS and now have an established list of tools and techniques frequently employed by staff. Lean and SS are considered robust CI methodologies capable of effectively delivering extensive benefits across many different categories. The NHS must overcome a sizable amount of highly important CFFs and divided organizational culture.Originality/valueThis paper has developed the most extensive empirical study ever produced on Lean and SS in the NHS and has expanded on previous works to create new and updated research. The findings produced in this paper will assist NHS medical directors and practitioners in obtaining up-to-date insight into Lean and SS status in the NHS. The paper will also guide the NHS to critically evaluate their current CI strategy to ensure long-term sustainability and deliver improved levels of service to patients.

Implementation of Six-Sigma methodology to achieve a competitive edge in Saudi universities

Six Sigma is a business process improvement method that aims to discover and eliminate the causes of defects, mistakes, and errors. Six Sigma is a process improvement methodology that focuses on critical processes that result in unacceptable defects to customers. This study aims to Implementation of Six-Sigma methodology to achieve a competitive edge in Saudi universities. For this purpose, we used the Scopus database for the data extraction; the PRISMA statement 2015 inclusion and exclusion framework is used to select data. Six sigma keywords are used in the search bar, and 12279 results are shown and follow the screening process. The final 48 articles and reviews are used for the systematic literature review after the detailed screening process. The results have classified the literature into three significant categories, organizational performance, Lean Six Sigma, and higher education. The Saudia Arabia universities are also focusing on the collaborative research work with the different regional and international universities for the Six Sigma implementation in universities. The study's findings of the study demonistrating that universities in Saudia are focusing on developing the education structure and methods using the Six Sigma methodology and Lean Six Sigma approach.

Application of the Methodology of Six Sigma in Public Health Institution

New world trends in product quality assurance and processes in companies around the world are based on quality control in all processes (basic and logistics). Quality control is in all processes: receiving requests from clients, implementation of required services, issuing final results, maintenance of instruments, procurement, providing quality and trained staff, and commercial service. Health care institutions in Republic of North Macedonia has got old models of management. By accepting the new world philosophies, the healthcare institutions are oriented towards a different quality system, transformation of the organizational structure, patient involvement, monitoring the key processes, implementing data management tools and team work. The TQM (Total Quality Management) system in a healthcare institution is based on the main principles of this philosophy: sanitary standardization, full commitment of patients, involvement of all employees in the organization and teamwork, continuous improvement and implement of six sigma methodology. The aim of the research is to implement and apply the six-sigma methodology as a tool for improving business processes in the Public Health Institution. With proactive application of the methodology six sigma in the department of clinical microbiology were determinedbusiness processes, potential operational errors, statistical processing of the obtained data and finding a solution for the identified defects in business processes. The research conducted in the Department of Clinical Microbiology showed that with the practical application of the 6-sigma methodology, excellent improvements were obtained in all business processes by: involving more employees, correction the time for delivery of materials to admission department, and complete training for employees.

Six-Sigma Methodology for Quality Monitoring in a Teaching Hospital Biochemistry Laboratory in Nepal

Introduction: Six-sigma is emerging method of choice for performance testing of clinical laboratory. This study was designed to evaluate the performance of 12 routine biochemical analytes on sigma-scale and calculate the quality goal index (QGI). Methods: A cross-sectional study was conducted at Tribhuvan University Teaching Hospital (TUTH), Biochemistry Laboratory for 3 months. BT1500 and BT3500 automated biochemistry analyzers were used. Internal quality control (IQC) performed routinely for 12 clinical analytes for both control levels were recorded from both analyzers and used for calculation of coefficient of variation (CV%). Bias was estimated based on the average difference obtained for each analyte from the target values provided. Values for total allowable errors (TEa) were taken from Clinical Laboratories Improvement Act guidelines. Variables used for calculation of sigma values and QGI were CV%, percentage bias and TEa. Results: Both levels of control for alanine-aminotransferase (ALT) in BT1500 and only control level L2 for aspartate-aminotransferase (AST) in both analyzers showed the sigma value greater than six. Sigma-values between three and six were found for uric acid for both levels of control in both analyzers. Less than three sigma values were obtained for parameters urea, creatinine, albumin, triglyceride, total-cholesterol, alkaline phosphatase (ALP) and magnesium for both levels of control in both analyzers indicating the need towards improvement in these methods. Conclusion: The quality of test for urea, creatinine, albumin, triglyceride, total-cholesterol, ALP and magnesium were unacceptable. Hence, appropriate actions should be taken towards measurement method in these parameters to improve accuracy and report quality.

How to Apply System Analysis and System Thinking to Lean Six Sigma Initiatives

This study focuses on the Toyota production system (TPS) and Lean in relation to innovation. The authors examine the tools and behaviors adopted in the TPS that are absent in the Six Sigma (SS) programs and how these elements may influence innovation and quality. Finally, this research analyzes the hybrid Lean Six Sigma (LSS). System analysis involves assessing a business scenario to improve the situation, establishes the changes needed and required, and innovation and product quality as components of the system analysis. This paper undertook text excavating and focused cluster development on highlighting the level of the Lean Six Sigma representations, as explained in articles on the Lean Six Sigma, such as those that compare Lean and Six Sigma. An iterative cluster examination was adopted to understand the primary focus of research in this area. The analysis shows that there is less research on the intersection of TPS and LSS in the areas of philosophy, partners, and people. These areas represent the opportunity to enhance the application of process improvement methods.

Entropy-Based Lean, Energy and Six Sigma Approach to Achieve Sustainability in Manufacturing System.

This work proposes a Value Stream Mapping (VSM) to be used in manufacturing industry that combines Lean, Energy and Six-Sigma methodologies. Lean's VSM tool is amended to energy VSM so that the value-added and non-value-added approach can be used to determine the energy use and waste. In order to identify the maximum rejection or rework at a workstation, an entropy-based mathematical model is developed and a Lean-Energy-Six Sigma Value Stream Mapping (LESSVSM) is presented. The model can be used in manufacturing at product level where temperature and energy can be measured from input to output. The model has been implemented on a manufacturing system containing four workstations. The proposed LESSVSM model will help to industry to become more sustainable as it can minimize energy and waste in the case of rework and rejection. This study presents a systematic approach which researchers and practitioners can apply for sustainable manufacturing.

Health technology assessment through Six Sigma Methodology to assess cemented and uncemented protheses in total hip arthroplasty.

The purpose of this study is to use Health Technology Assessment (HTA) through the Six Sigma (SS) and DMAIC (Define, Measure, Analyse, Improve, Control) problem-solving strategies for comparing cemented and uncemented prostheses in terms of the costs incurred for Total hip arthroplasty (THA) and the length of hospital stay (LOS). Multinomial logistic regression analysis for modelling the data was also performed. Quantitative parameters extracted from gait analysis, electromyography and computed tomography images were used to compare the approaches, but the analysis did not show statistical significance. The variables regarding costs were studied with the Mann-Whitney and Kruskal-Wallis tests. No statistically significant difference between cemented and uncemented prosthesis for the total cost of LOS was found, but the cost of the surgeon had an influence on the overall expenses, affecting the cemented prosthetic approach. The material costs of surgery for the uncemented prosthesis and the cost of theatre of surgery for the cemented prosthesis were the most influential. Multinomial logistic regression identified the Vastus Lateralis variable as statistically significant. The overall accuracy of the model is 93.0%. The use of SS and DMAIC cycle as tools of HTA proved that the cemented and uncemented approaches for THA have similar costs and LOSy.

Light Fidelity (Li-Fi) overview and investigation into connection speed

Abstract The overarching aim was to reduce the frequency of connection failures that occur due to the connection speed and reliability, and identify, characterise and optimise the key process input variables (KPIVs). An experimental research approach with an inbuilt planned manipulation to one or more variables in the experimental data set was adopted. Key elements of the Six-Sigma methodology were applied to resolve the issue of high failures due to connection speed and reliability between two Li-Fi transceivers. KPIVs were successfully identified, characterised and optimised to implement a permanent corrective action to ensure a reduction in connection failures from 17% to 0%. The alignment between two Li-Fi transceivers along with Li-Fi cut-out was found to be critical in achieving good connection speed and reliability. The interference due to ambient visible spectrum lighting found to be statistically insignificant. This study explored the application and benefits of accessible wireless data communication technologies. Moreover, it sheds light on the probable factors that may influence Li-Fi connection speed and areas for future research. The current research provides a Six-Sigma based solution to high connection failure rates while using an infrared-based Li-Fi transceiver. Results also offer insights into the analytical tools that were found to be effective during the problem-solving process.

Bed downtime: the novel use of a quality metric allows inpatient providers to improve patient flow from the emergency department

BackgroundEmergency department (ED) boarding time is associated with increased length of stay (LOS) and inpatient mortality. Despite the documented impact of ED boarding on inpatient outcomes, a disparity continues to...

The effect of critical success factors in the application of six sigma methodology on the quality of construction projects' output

Purpose: This study aims at determining and understanding the critical success factors in order to apply the six sigma methodology in construction organizations to ensure reaching a higher level of construction organizations' output. The main purpose is divided into the following secondary objectives:- Determining the effect of each of the critical success factors (management support, project selection and execution of six-sigma) in the success of the application of six-sigma methodology in construction organizations.- Determining the effect of critical success factors altogether (support management, project selection and execution of six-sigma) on the quality of construction organizations' output.Research Methodology:This study used the quantitative (descriptive analytical) method through using practical method for the purpose of collecting and analyzing information, and testing hypotheses.Research limitation: Human limit: It is represented by workers in Jordanian construction organizations.- Place limit: Jordanian construction organizations in the capital city of Amman.- Time limit: The period of time it took to accomplish the study (7-9/2020).- literature limit: To determine the variables of critical success factors, the researcher referred to previous studies (Bhaji & Antony, 2001), (Goldstein, 2001), (Kwak & Anbari, 2006), (Hakeem Khan, 2005), (Urdhwareshe, 2004), (Buch & Tolentins, 2006), (Martins et al., 2006), (Coronel et al., 2009), (Johnson & Cale twohill, 2008), (Shahin, 2010), (Brun, 2010), (Gosnik & Vujicaherzog, 2010), (Zailani & Sasthriya, 2011), (Padhy & Sahu, 2011), (Kanjanpanykom & Kungvol, 2011).Originality/ value of the study:This study helps in finding out the factors of success in the application of six-sigma methodology, and how much they affect the quality of construction organizations' output. This will help find out the level of quality of construction project's output in terms of speed, cost and precision in results, which will help the improvement mechanism. This in turn will help the construction organization produce high-quality output, which will help the construction organization achieve competitive advantage, and lead to its continuity to work, thus the continuity of organizations, which have vertical association with the construction organization in work too, and this will lead to turning the wheels of the national economyFindings: Results of Statistical Analysis indicate that the relative importance of critical success factors in applying the approach of six sigma in a middle level of importance. Whereas, the arithmetic averages have ranged between (2.77-3.58). Moreover, Results of Statistical Analysis of this study indicate a positive impact on the outcomes of construction organizations for combined critical success factors which are; Senior Management support Factor, Project Selection, Implementation factor of six sigma. Furthermore, Results of Statistical Analysis indicate a positive impact of applying six sigma approach on the quality of the outcomes of construction organizations. Key Words: critical success factors, six sigma approach, management in quality assurance in construction projects

Klinik Laboratuvarımızın Toplam Kalite Performansının Altı-Sigma Yöntemiyle Değerlendirilmesi

Aim: In order to evaluate the performance of the clinical laboratories, a quality measurement method, The Six-Sigma Methodology, is used. We aimed to evaluate the analytical performance of our clinical laboratory by using the internal and external quality control data of 28 analytes, and by calculating their process sigma values. Methods: Sigma values of 28 analytes of our laboratory were determined from coefficient of variation (CV %) and bias for 3 subsequent months from December 2018 to January 2019. If the sigma values are >6, between 3 and 6, and <3, they are classified as »world-class«, »good« or »un-acceptable«, respectively. Results: 6 (21%) analytes; T Protein, Creatinin, Ca, Na, Cl, HbA1c; provided <3 sigma value, 1 (04%) analyte; lipase; provided between 3-6 value and 11 (39%) analytes; amylase, GGT, ALT, LDH, CRP, Lactate, BUN, Direct Bil., T Bil., CK and CK-MB; provided > 6 sigma value for both IQC1 and IQC2 levels for three consecutive months, respectively. Conclusions: In terms of Six-Sigma Metrics; our results were generally found as world-class or good. An appropriate quality control scheduling should be carried out for each test by using Six-Sigma Methodology in all clinical chemistry laboratories.

APPLICATION OF LEAN SIX SIGMA TO REDUCE PATIENT WAITING TIME: LITERATURE REVIEW

APPLICATION OF LEAN SIX SIGMA TO REDUCE PATIENT WAITING TIME: LITERATURE REVIEW

Integration model of total quality management and six sigma in hospital quality management

Implementation of quality management is very important for hospitals to improve processes, solve problems, and reduce variations and errors in service, including through the implementation of popular Total Quality Management (TQM) and Six Sigma (SS) as new quality management strategies to increase profitability, effectiveness and efficiency of the organization's operations to meet customer’s needs. This study aims to develop an integrated hospital quality management model from the practice of TQM and SS to provide synergy in improving hospital performance. The study design was cross sectional through a survey using a questionnaire on 863 respondents, namely all employees ranging from doctors to administrative personnel at 8 hospitals. The TQM and SS practice integration model identified as “Quality Management Alliance Model (QMA)” consists of 6 variable constructs, namely: Management Practice (MP); TQM Infrastructure Practice (IPTQM); SS Infrastructure Practice (IPSS); Core Practice TQM (CPTQM); Core Practice SS (CPSS); and Hospital Performance (KRS) with 12 structural equations hypothesized. Data analysis are performed using Structural Equation Model through 2 tests, namely analysis of measurement models using confirmatory factor analysis (CFA) second order approach and structural model analysis. The results of the first order confirmatory factor analysis (CFA) analysis, after issuing invalid indicators (SLF≤0.5 and t≤1.96), obtained constructs of latent variables with models fit, valid, and reliable. Then in the second order CFA analysis on the overall model after being simplified through LVS (latent variable score) the study obtained construct model fit, valid and reliable. The results of the structural model analysis obtained a model fit with 11 structural equations that are positively and significantly related (t> 1.96). This study proves that the QMA model is feasible and can be applied to measure the implementation of hospital quality management. Hospital management is recommended to implement the QMA Model optimally to improve performance.

A Six Sigma DMAIC methodology as a support tool for Health Technology Assessment of two antibiotics.

Health Technology Assessment (HTA) and Six Sigma (SS) have largely proved their reliability in the healthcare context. The former focuses on the assessment of health technologies to be introduced in a healthcare system. The latter deals with the improvement of the quality of services, reducing errors and variability in the healthcare processes. Both the approaches demand a detailed analysis, evidence-based decisions, and efficient control plans. In this paper, the SS is applied as a support tool for HTA of two antibiotics with the final aim of assessing their clinical and organizational impact in terms of postoperative Length Of Stay (LOS) for patients undergoing tongue cancer surgery. More specifically, the SS has been implemented through its main tool, namely the DMAIC (Define, Measure, Analyse, Improve, Control) cycle. Moreover, within the DMAIC cycle, a modelling approach based on a multiple linear regression analysis technique is introduced, in the Control phase, to add complementary information and confirm the results obtained by the statistical analysis performed within the other phases of the SS DMAIC. The obtained results show that the proposed methodology is effective to determine the clinical and organizational impact of each of the examined antibiotics, when LOS is taken as a measure of performance, and guide the decision-making process. Furthermore, our study provides a systematic procedure which, properly combining different and well-assessed tools available in the literature, demonstrated to be a useful guidance for choosing the right treatment based on the available data in the specific circumstance.

Radial Basis Function Neural Network for the Evaluation of Image Color Quality Shown on Liquid Crystal Displays

The color quality of an image shown on a liquid crystal display (LCD) can be measured with a spectroradiometer; however, this instrument is expensive, work under controlled illumination conditions with an artificial source of light, and measurements take a long time. A spectroradiometer returns measurements of wavelength or CIE color space. A low-cost and fast alternative consists of using a digital camera that outputs RGB measurements. Unfortunately, comparisons between measurements obtained with both instruments cannot be performed; hence, conversion equations must be used. The main problem is that equations do not consider the effects caused by the camera lens, sensor variations, and configurable parameters such as gain and the exposure time. This paper proposes the architecture of a radial basis function neural network (RBFNN) to measure the image color quality displayed by an LCD using a digital camera. The RGB values acquired with a camera are used as inputs to the RBFNN. The output predicted the luminance and chromaticity components in the CIExyY color space and included the corrections to the lens and camera parameters. First, the RBFNN topology is explained, including the calculation of the number of neurons in the hidden layer, and the definition of the dispersion centers and their associated spread. Next, the experiments related to RGB color space reconstruction and conversion from RGB to CIE are presented. The proposed approach was tested on a real automotive scenario. The results obtained were similar to those measured with the spectroradiometer with an accuracy of 93.3%. Moreover, the results remained within limits established by the six-sigma methodology.

Cost of poor quality reduction in auto sector: an exploration with Six-Sigma

The cost of poor quality (COPQ) always helps in analysing the operating costs for effective and profitable business management. COPQ consists of those costs which are generated as a result of producing defective material. The present study deal with implementing the Six-Sigma in the Indian automobile company. This research aims to reduce the problems faced by the company's quality inspection department. The department faces various rejection problems of two vehicles, such as front fork pivot hard movement, grease nipple broke, O-rings struck, edge bends, etc. We used a structural DMAIC methodology to improve the process. This study used multiple Six-Sigma tools such as Pareto chart, process map, fishbone diagram, and process capability chart to solve the rejection problem. Using a Six-Sigma methodology, we improved the sigma level of 1.875 to 4.375, which benefits 199,020 rupees' rework costs annually. This study helps practitioners and academicians to emphasise their effort towards COPQ.