Statistics Article

Multiple Authors
By: Scott A. Hindle, Donald J. Wheeler

In theory, a production process is always predictable. In practice, however, predictable operation is an achievement that has to be sustained, which is easier said than done. Predictable operation means that the process is doing the best that it can currently do—that it is operating with maximum consistency. Maintaining this level of process performance over the long haul can be a challenge. Effective ways of meeting this challenge are discussed below.

John Flaig’s picture

By: John Flaig

Story update 9/26/2017: The words "distribution of" were inadvertently left out of the last sentence of the second paragraph.

Some practitioners think that if data from a process have a “bell-shaped” histogram, then the system is experiencing only common cause variation (i.e., random variation). This is incorrect and reflects a fundamental misunderstanding about the relationship between distribution shape and the variation in a system. However, even knowledgeable people sometime make this mistake.

Ville Satopaa’s picture

By: Ville Satopaa

At a 1906 livestock show in Plymouth, England, nearly 800 people participated in a contest to guess the weight of a slaughtered ox. The average of these estimates was 1,197 pounds. This is remarkable because the true weight of the ox turned out to be 1,198 pounds. The average was only one pound away from the truth. How could it be so accurate? Perhaps by chance?

Barbara A. Cleary’s picture

By: Barbara A. Cleary

If you get off the highway and take an alternate route when traffic slows to one lane, you are making a prediction. Likewise, if you decide to invite someone to dinner, that too is a prediction. The scientific method? Predictive in nature. Every time you make a decision, you are making a prediction of an outcome, and choosing one over another based on this prediction.

Dirk Dusharme @ Quality Digest’s picture

By: Dirk Dusharme @ Quality Digest


Our August 11, 2017, episode of QDL looked at the role of technology in after-market service, stairs that help you up, Fidget Cubes, and more.

“Climbing Stairs Just Got Easier With Energy-Recycling Steps”

These stairs actually help you go up.

Multiple Authors
By: Phil Klotzbach, Michael M. Bell

June 1 marked the official start of the Atlantic hurricane season, which runs through the end of November. It’s a busy time for us at the Tropical Meteorology Project in Colorado State University’s (CSU) Department of Atmospheric Science, where we are issuing our 34th annual Atlantic basin seasonal hurricane forecast.

John Niggl’s picture

By: John Niggl

Ever wondered why quality control (QC) professionals check a sample instead of 100 percent of a shipment during inspection? Or maybe you’ve wondered why they use acceptance sampling, rather than simply inspecting an arbitrary quantity of goods, such as 10 or 20 percent?

Steve Daum’s picture

By: Steve Daum

I have daily conversations with manufacturer plant managers, quality managers, engineers, supervisors, and plant production workers about challenges when using statistical process control (SPC). Of the mistakes I witness in the application of SPC, I’d like to share the five most prevalent; they can be costly.

Derek Benson’s picture

By: Derek Benson

How early is too early to introduce quality into your everyday life? Have we missed out on improvement opportunities in our personal lives along our paths to achieving our career goals as quality professionals? These questions have me pondering how life could have been different for me growing up with a little more emphasis on data analysis for improvement.

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