The key of sustainable development of companies is continuous improvement & innovation, the foundation of conducting both activities relies on sufficient profit to acquire adequate resources. Sufficient profit can be greatly achieved by implementing methodology of quality management & lean six sigma in order to maximize value of the products & services companies provide while minimize the quality & operating cost of the value added processes for their products & services. Then, increase customer satisfaction & company reputation in the long run. The core principle of quality management is process control which is analogous to variation control. Unfortunately, for most IATF suppliers I have audited in the past, the true meaning of quality management is never properly understood by most of them, they just spend money to get the certificate in order to be part of automotive supplying chain and only keep minimum requirements asked by IATF forever without trying to understand the source of variation that affecting their QMS, then improve their QMS with tools like APQP, FMEA, MSA, SPC. Most suppliers just use these tools to submit homework when PPAP documentation is requested without knowing how to analyze the results and applying it for continuous improvement or use more sophisticated statistical tools like ANOVA, ANCOVA, MANOVA, linear regression, response surface, fraction factorial experiment even PCA and factor analysis for better understanding both effectiveness & efficiency of their value-added processes. Ironically, it seems the so-called accreditation bodies that issuing the certificate DO NOT point out this fundamental problem during their periodical audit to validate suitablility of their certificate. A typical misunderstanding about quality management is to “foster a mentality of Zero Defect”. Undoubtedly, this is ultimate goal for quality management but is not always economical benefit to achieve due to the presence of different kinds of variations at production environment resulted in potential defective items, it could be costly to remove all these variations more than the profit earned from producing these items which is opposed against the business nature of companies to make profit, and the trade-off has to be made. I believe to “foster a mentality of studying source of variation” rather than “foster a mentality of Zero Defect” would be more practical & helpful for quality management & improvement that companies could benefit from it in the long run. No company can become “first class supplier” standing out from their competitors with “third class subcontractors” of poor quality management. As an enthusiast and practitioner of quality control and continuous improvement with more than 8 years working at automotive supplying chain, I am always willing to devote what I learn to help companies, their subcontractors & suppliers that are struggling with sluggish improvement of quality management system by using a variety of statistical tools to study sources of variation for a win-win for all involved stakeholders.