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Latest "Six Sigma" Posts

Use XmR Charts instead of c, np, p and u Charts

I have found that an XmR chart is the easiest way to display attribute data. Simply convert the numerator/denominator into a ratio and plot the ratio. defects per day could be a c chart, but an XmR chart works just as well defects/samplesize could be np, p or u chart, but XmR chart works just as […]

Posted by Jay Arthur in QI Macros, Six Sigma, Statistics.

What USL/LSL Do I Need for Cp>1?

Customer asked me what seemed like a strange question: What specification limits do I need to get a Cp greater than one? Usually her customer should set specification limits, but her boss wanted to know what they could deliver. Hmmmm! Then I realized that since QI Macros templates (e.g., XmR chart) calculate the average and […]

Posted by Jay Arthur in QI Macros, Six Sigma, Statistics.

Cpk and Hard vs Specification Limits

A customer called upset about Cpk. He had a runout of 0.010, but was getting a very low Cpk. Turns out he’d made the classic mistake of confusing a hard limit (e.g., zero) with a specification limit. I had him use QI Macros with an Upper Specification limit (USL) and no Lower Specification Limit (LSL). […]

Posted by Jay Arthur in QI Macros, Six Sigma.

Mistake-proofing Bathroom Design

My friend, Mary LoVerde’s ezine shows a hotel bathroom she recently experienced. How would you mistake-proof this design? What are the possible failure modes and effects (FMEA)?

Posted by Jay Arthur in QI Macros, Six Sigma.

Is Fear of Math Holding You Back?

Many people avoid Six Sigma because they think it involves a lot of math and statistics. You know, formulas. I don’t think you need any formulas. You don’t need to be a statistician. You just need software that went to college and knows the formulas. In The Math Gene, Author Keith Devlin explores “why so […]

Posted by Jay Arthur in QI Macros, Six Sigma.

Quality Tool Usage at IHI 2016 Poster Presentations

I’ve been monitoring the use of quality tools at the Institute for Healthcare Improvement conference for over a decade. This year there was a slight uptick in the use of control charts, but still far below my expectations. How can healthcare hope to achieve and sustain improvements without control charts? There were over 500 posters, […]

Posted by Jay Arthur in healthcare, QI Macros, Six Sigma.

Statistical Bullies

At IHI, I spoke with one Quality Improvement Adviser who was getting blow back from certain statisticians in her organization. They were challenging her methods and tools and analysis. As I have written before, I call these folks “Stat Bastards” because they belittle others rather than help them. As a member of the American Statistical […]

Posted by Jay Arthur in Six Sigma, Statistics.

Bad at Math?

At the IHI 28th Forum in Orlando, one visitor to our exhibit booth said: “I’m bad at math.” She was worried about needing to learn formulas. I hear this same concern from most people thrust into quality improvement. I told her: “You don’t need to know formulas. You just need to know how to select […]

Posted by Jay Arthur in Excel, QI Macros, Six Sigma.

The Great Training Robbery

October 2016 HBR article, Why Leadership Training Fails-and What to Do About It, calls the $160 Billion spent on training in the U.S. the Great Training Robbery. The authors say: “Learning doesn’t lead to better organizational performance, because people soon revert to their old ways of doing things.” Unfortunately, this is true of most Six Sigma […]

Posted by Jay Arthur in healthcare, Lean, Manufacturing, Service, Six Sigma.

Nobody Wants to Read Your Spreadsheet!

Nobody wants to read your spreadsheet! No matter how hard you try to make it pretty, create great labels or whatever, the only person who can read your spreadsheet is a CFO or Excel spreadsheet geek. And the Excel geek is going to tell you 10 ways to make it prettier. The purpose of data […]

Posted by Jay Arthur in Data Mining, QI Macros, Six Sigma.