The remainder of this thesis has been structured as follows.
Chapter 2 begins with a review of the literature on Lean, in relation to manufacturing systems, its applications, associated issues, and limitations. This chapter also covers the relevant literature on Statistical Thinking, Continuous Improvement (Continuous Improvement is inherent in Lean thinking), Six Sigma (a quality and systems improvement approach), and Lean Six Sigma (a variant of Six Sigma). The chapter concludes with the key points carried forward to the next chapter (Chapter 3) to frame the research questions.
Chapter 3 continues the literature review by covering the relevant product quality improvement literature that involves experimentation. More specifically, Chapter 3 provides the basic literature on the traditional DoE approach (as a background to understand and critically review the literature on RPD approaches), the literature on Taguchi’s RPD approach (much of Chapter 3 covers this subject area) as well as the major alternative approach advanced by statisticians—the “response surface alternative to Taguchi’s RPD approach” (Khuri & Mukhopadhyay, 2010). Towards the end of the chapter (section 3.6), the researcher highlights the knowledge gaps and the corresponding research questions of the study.
Chapter 4 covers part of the methodology. This chapter begins with a review of research paradigms available and justification of the particular paradigm chosen by the researcher. This is followed by theoretical model development, through an extensive literature review. The model explains the relationships between Taguchi’s Quality Philosophy, the Lean Manufacturing System, and the operational outcomes, through the mediating effect of Continuous Improvement. Thereafter, the chapter describes the development of the survey questionnaire (through the literature) to collect data to test the theoretical model (see Appendix A for the questionnaire). This is followed by a description of how the sample was selected to administer the survey among Lean
apparel manufacturing factories in Sri Lanka (all factories belonged to the case study organisation to ensure that the organisational context remains Lean apparel manufacturing) as well as how the data were actually collected and coded for data analysis. Furthermore, Chapter 4 explains the methods and strategies that were used to assure the methodological rigour, such as assuring reliability, validity, and lack of method bias. In essence, this chapter answers the first research question (RQ1). Parts of this chapter have been published in two conference proceedings. An overview of the study was presented at the 2012 World Business Capability Congress (Gamage, Jayamaha, & Grigg, 2012) while the theoretical model development was presented at the 11th ANZAM Operations, Supply Chain and Services Management Symposium (Gamage, Jayamaha, Grigg, & Nanayakkara, 2013).
Chapter 5 covers the remaining portion of the methodology. This chapter begins by reviewing the relevant literature on the case study methodology. The apparel manufacturing factory (based in Kandy, Sri Lanka) in which the case study was conducted is introduced immediately afterwards (the researcher collected experimental data as well as qualitative data at this factory). This is followed by the data collection methods and strategies. Quantitative data were collected to conduct statistical analysis, among other things, to identify robust parameter settings. Qualitative data were collected to identify the operational merits and demerits of using Taguchi methods over conventional DoE methods on RPD, as well as to understand the forces (drivers and restraints) that affect implementation of Taguchi methods.
Chapter 6 begins with the demographic information of the data collected through the questionnaire. Since the theoretical model contains latent variables, concepts related to latent variables are covered in this chapter, prior to introducing the statistical concepts on Structural Equation Modelling (SEM) and related concepts. This is followed by the presentation of the results on the validity and reliability of the measurement scales used in testing the theoretical model, based on the survey data. Upon completion of model testing, within Chapter 6, the researcher interprets the results from a theoretical and practical perspective, through a discussion section. In essence, this chapter answers the second research question (RQ2). Some sections of this chapter (theoretical model testing) have been published as a conference proceeding at the 12th ANZAM Operations, Supply Chain and Services Management Symposium (Gamage, Jayamaha,
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Grigg, & Nanayakkara, 2014b). The paper won the best paper award at the conference (Appendix B).
Chapter 7 provides an analysis of the test results on Taguchi’s RPD approach and the alternative DoE approach (a response surface alternative to Taguchi’s RPD approach). This is followed by the presentation of the optimum parameter settings (the optimal level to be set for each controllable factor) to minimise variation to improve product quality. Thereafter the researcher provides a comparative analysis (a discussion) between the two methods from a statistical and operational perspective, based on her experience in solving the quality improvement problem. In essence, this chapter answers the third research question (RQ3). Some parts of this chapter (the experimental design) have been published in form of a conference proceeding at the 2014 IEEE International Conference on Industrial Engineering and Engineering Management (Gamage, Jayamaha, Grigg, & Nanayakkara, 2014a).
Chapter 8 uses “Force Field Analysis” (Lewin, 1951) as an analytical tool to identify the drivers and restraints that govern organisational change, when Taguchi methods are actually being introduced in a mature Lean apparel manufacturing environment. In effect, this chapter answers the final research question (RQ 4). The chapter discusses organisational change management issues, based on the findings (qualitative) of the researcher’s case study. This achieves the general research objective of the study.
Chapter 9, the final chapter covers the summary of the findings in relation to the research questions and research objectives. Finally, the limitations of the study and directions for future research work are presented in this concluding chapter, along with the researcher’s final thoughts.
Figure 1.2 depicts the links between the research questions, research objectives, findings, and the thesis chapters.
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F
igure 1.2
:
The links bet
w ee n the rese arc h qu estions, re sea rc h obje ctives, f inding s and the th esis ch apter s