Where Do Manufacturing Specifications Come From?Standard deviation of conditional distribution of X given Y is the reason all measurement studies are built upon repeated measurements.
Tue, 07/06/2010 - 08:40
Evidently Steven Ouellette did not like my June column, “Is the Part in Spec?” The adjectives he used were “complicated,” “unhelpful,” “backward,” “confusing,” “unnecessary,” “crazy,” and “disastrous.” (Ouellette’s response, “Know the Process… Is the Part in Spec?Since data is always imperfect, how can we ever know if a measured item is within the specifications?
Tue, 06/01/2010 - 10:02
During the past 20 years it has become fashionable to condemn measurement processes that are less than perfect. Yet the reality is that we must always use imperfect data. Given this fact of life, how can we ever know if a measured item is or is not… Two Routes to Process Improvement--Part 2Assignable causes and common causes
Thu, 05/06/2010 - 07:00
Having an effective model for the nature of data will inevitably identify two different paths to process improvement. One path seeks to operate a process up to its full potential while the other path seeks to operate to meet requirements. This… Two Routes to Process Improvement--Part 1Cause-and-effect relationships
Wed, 05/05/2010 - 07:00
Having an effective model for the nature of data will inevitably identify two different paths to process improvement. One path seeks to operate a process up to its full potential while the other path seeks to operate to meet requirements. This… The Imaginary Theorem of Large SamplesHow many data samples do you need?
Mon, 04/05/2010 - 10:10
Courses in statistics generally emphasize the problem of inference. In my December column, “The Four Questions of Data Analysis,” I defined this problem in the following manner:
Given a single unknown universe, and a sample drawn from that… Scaling Factors for Process Behavior ChartsA quick reference guide
Mon, 03/01/2010 - 05:00
In the 1940s the War Production Board trained approximately 50,000 individuals in how to use process behavior charts (also known as control charts). At that time the computations were done by hand, and the emphasis was on making things as easy as… Individual Charts Done Right and WrongHow does your software rate?
Mon, 02/01/2010 - 05:00
In my column of Jan. 7, “The Right and Wrong Ways of Computing Limits,” I looked at the problems in computing limits for average charts. This column will consider the right and wrong ways of computing limits for charts for individual values. As… The Right and Wrong Ways of Computing Limits How does your software measure up?
Thu, 01/07/2010 - 05:00
Today virtually everyone uses software to create process behavior charts, yet the available software is notoriously unreliable in terms of the way the limits are computed. This column will explain and illustrate the difference between the correct… The Four Questions of Data AnalysisHomogeneity is the primary question of analysis.
Tue, 12/01/2009 - 05:00
The four questions of data analysis are the questions of description, probability, inference, and homogeneity. Any data analyst needs to know how to organize and use these four questions to be able to obtain meaningful and correct results.
The… Two Definitions of TroubleLead us not into the Cycle of Despair
Mon, 11/02/2009 - 04:00
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n the past there was only one criterion required to be a good supplier: you had to ship very few nonconforming items. If your proportion of nonconforming items took a turn for the worse then you would be “in trouble,” and you would stay in…
