Category: Tools & Techniques

The best way to develop a CTQ tree is the form of a cause-and-effect matrix.  Locate CTQ’s on columns and CTP’s on rows.  Each column-row intersect constitutes a “causal opportunity,” the strength of which must be rationally measured or otherwise evaluated.

As you likely know, the Poisson distribution is an approximation of the binomial.  In general form, the Poisson function is given as Y = (np^r * e^-np)/r!, where n is the number of trials, p is the event probability, and r is the number of event occurrences.  By direct substitution, we assert that Y = […]

As stated in your question, the project is focused on the “attrition rate of employees.”  At first glance, this would appear to be a problem – not a process.  Given the problematic perspective, we must recognize that “attrition rate” is a critical-to-value characteristic (CTV).  As such, it should be known as the dependent variable (primary […]

Obviously, a suggested course of action should be quite guarded, as it would be very case sensitive (i.e., circumstantial by nature).  As we all know, some consultants make their living resolving such “catch 22” situations.  We also recognize that the ability to find a balance point is more art than science.  It is much like […]

1) There is no such thing as a one-size-fits all Black Belt or Green Belt program of study. 2) Many customers are naïve.  They often want more tools (not fewer), regardless of whether or not they will ever be used. 3) Some customers seek to purchase a hardware store so as to fix the kitchen […]

Under the condition that D = 0 defects for the constrained condition of N = 20 samples, we can statistically approximate the short-term capability and provide its quantity in the form Z.st = 3.33.  Of course, this is directly equivalent to Cp = 1.11. Interestingly, the statistical base underpinning this set of computations is fully […]

There is little difference between Statistical Quality Control (SQC) and Statistical Process Control (SPC).  At one time, there might have been some philosophical separation, but today, they exist as general synonyms.  Some prefer SQC because the idea of “quality” is larger and more encompassing than that of “process.”  Others counter this by pointing out that […]

Establishing the initial list of potential causes is often more art than science.  Unfortunately, the brainstorming process is still one of the best ways to surface candidate variables.  However, there are several other alternatives: 1)   Query process experts. 2)   Benchmark similar processes. 3)   Review the literature. 4)   Perform an Internet search. 5)   Conduct correlation study. […]

To facilitate an answer, we will consider three examples.  First, consider the game of baseball.  We understand the field-of-play consists of 9 positions.  The coach is “free” to assign any of the 9 players to any of the 9 positions. Once the 8th player is assigned to the 8th position, the 9th player-position is pre-determined, […]

Suppose we consider a specific bilateral critical-to-quality characteristic (CTQ).  In other words, we are in view of a key design feature that sports a two-sided performance specification.  If a bilateral design margin of “Y percent” was to be imposed on the given CTQ (during the course of product configuration), we indirectly and necessarily infer the […]

Let us suppose we are interested in testing the influence of a certain independent variable (say, A) as it relates to a given dependent variable (say, Y).  We will suppose the experimental factor (variable A) is to be tested at two competing settings (test levels).  In this scenario, the two levels will be called “high” […]

Arguably, acceptance sampling is an effective and efficient means to ensure the proper surveillance of product and service quality.  Using this approach, a random sample (of product or service) is inspected or tested to determine if the observed level of quality is acceptable or unacceptable.  If the sample supports the hypotheses of unacceptability, then certain […]

Please recognize that the “art and science” of process mapping is quite generic by nature.  You should apply the mapping tools, techniques, and procedures in the given situation just as you would in any other type of situation.  Granted, the variable labels will change – but that’s about it.  Simply stated, you must define what […]

Thanks to modern technology, we have before us a virtual mountain of information.  On the Internet, we can find many case studies on the subject of DOE (design-of-experiments).  For a wide area success stories and general discussion, you may want to visit the following websites: 1) http://www.statease.com/articles.html2) https://www.isixsigma.com/tt/doe/3) http://class.et.byu.edu/mfg340/lessons/designofexperiment/4) http://members.cox.net/asqsd/kn/publications.htm In addition to these sources, […]