Six Sigma

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Confidence Interval Approximations

What are some of the standard approximations for confidence intervals, and when are they used? First, let’s review the definition of a confidence interval. Confidence Interval: A range of values so defined that there is a specified probability that the value of a parameter lies within it. Example for the most common parameter: the mean. [...]

The Power of a Statistical Test

What is the power of a statistical test and why use it? Power is the probability of making a correct decision (to reject the null hypothesis) when the null hypothesis is false. To determine it, one needs to assume a particular alternative hypothesis. Because power focuses on “making a correct decision” it is natural to [...]

2019-06-16T07:22:02+00:00 By |Tags: , , |0 Comments

Integrating Simulation with DMAIC

First, let’s review the objectives of each DMAIC step. D: Define (Establish project purpose and scope, background on process and customer) M: Measure (Quantify existing process performance) A: Analyze (Determine ways to eliminate or reduce the gap between current performance and project goals) I: Improve (Evaluate, select, and implement chosen solution) C: Control (Institutionalize the [...]

Simpson’s Paradox: Be Wary of Aggregate Data

Simpson's paradox occurs when a trend appears in several different groups of data but disappears or reverses when the data from these groups are combined. In this video, Guillaume Riesen, currently a Ph.D. student in neuroscience at Stanford University, gives examples of how combining data from two disparate groups can lead to a different and [...]

Quantifying Agreement Among Assessors

How well do your inspectors agree with one another? How well do they agree with a standard? What about people who review documents? How would several reviewers rate the same document? Do they agree with one another? These are just several of the situations where Attribute Agreement would answer these questions. In this simple video, [...]

Using Excel Solver for Optimization

Do you have a problem with an objective to maximize, minimize, or perhaps you want to hit a target value? Is achieving your objective based on the provision of several resources for which there are constraints? Then you have an optimization problem on your hands, which requires mathematical programming.  But don’t worry. You most likely [...]

2019-04-20T19:04:08+00:00 By |Tags: , |0 Comments

Essential Project Elements: Creating a Work Breakdown Structure and a PERT Chart

A Work Breakdown Structure (WBS) divides a project into smaller, manageable pieces. It helps organize the work required.  A PERT chart works in concert with a WBS to organize and schedule required tasks. PERT stands for Program Evaluation Review Technique.   Nathan Garrett, a professor at Woodbury University in Burbank, California, uses a simple example [...]

Andon at Ensto Energy

Andon is a manufacturing term referring to a system to notify management, maintenance, and other workers of a quality or process problem. Andon, in Japanese, means “paper lantern.” So, it is an appropriate term for “illuminating” a problem. Ensto, a Finland-based energy company, uses an Andon system to ensure world-class quality. Whenever a problem arises [...]

2019-03-23T20:20:05+00:00 By |Tags: , , |0 Comments

TRIZ (The Theory of Inventive Problem-Solving)

TRIZ is a systematic approach to solving problems. It was invented by Soviet inventor Genrich Altshuller and his colleagues, starting in 1946. Altschuller reviewed 40,000 patents to determine the principles that were used for the inventions. As a result, he developed 40 principles of invention, coupled with a Contradictions Matrix. These are just a few [...]

The Principles of Jidoka or Autonomation

In this YouTube video, Tom Huckabee, Development Specialist for Processes and Information Systems, explains Jidoka or autonomation and its basic principles. He defines Jidoka as a “device to auto-stop a process to prevent a defect or a problem.”  The key is the automatic part. Huckabee breaks the principle of Jidoka into a few simple steps: [...]