What is the best way to explain why we do not calculate three-sigma control limits directly from the data points themselves? In other words, for an x-bar or R-chart, why don't we calculate the standard deviation for the 25 or 30 sample means or sample ranges as an estimate of sigma and then multiple that by three? Or, for an individuals chart, why can't we calculate the standard deviation of 25 or 50 individual measurements and then multiple that by three to obtain three-sigma control limits?
Does someone have a good way to explain this to others?
qdigest 12/3/2001
I think that Firebrew provided a useful starting point for your contemplation of a new name for your department. Let me provide some additional information that may be helpful with your definition search.
ISO 9000:2000, Quality management systems. Fundamentals and vocabulary, is the source for all definitions used in ISO 9001:2000 and ISO 9004:2000 when a dictionary is not enough, so to speak. ISO 9000:2000 contains definitions for three terms that I will provide to help you understand how the quality experts behind the ISO 9000 series conceive of things:
3.2.1, system, set of interrelated or interacting elements
3.2.2, management system, system to establish policy and objectives and to achieve those objectives
3.2.3, quality management system, management system to direct and control an organization with regard to quality
The three are related to each other and in a sense support each other. However, you mention that your organization has an "integrated management system", which means that it goes beyond just quality management. What about IMS Department, if what your department does is support and assess the effectiveness of the system?
I guess two important questions you should answer in choosing a new name are:
1. What is your department's present name and is it totally out-of-date?
2. What does your department do and could you describe its activities in 10 words or less?
If the name is totally out-of-date and you can describe your department's activities in 10 words or less--or at least its key activities--then see if something in that description could be boiled down to a short title.
Someone I have worked with recently on an article would probably recommend PMD for Process Management Department. And let us know what the new name is once decided!
firebrew 11/20/2001
Let me take a stab at this.
I suggest that "Quality Management System" as used in the ISO/QS/AS/TL 9000 series of standards, refers to:
" A business management methodology that ensures success through causing Quality outcomes in every task and activity throughout the organization."
Rather than being merely a "Quality System", the intent is to decribe how a business operates. What it intends to accomplish, how it intends to do it, and what values and beliefs it embraces to guide those activities.