Statistics Features

Ryan McKenna's picture
Ryan McKenna
To date, this series focused on relatively simple data analyses, such as learning one summary statistic about our data at a time. In reality, we’re often interested in a slightly more sophisticated...
Donald J. Wheeler's picture
Donald J. Wheeler
For more than 40 years it has been common to use the precision to tolerance ratio (P/T ratio) to compare the standard deviation of measurement error with the specified tolerance for a...
David Darais's picture
David Darais
In our last article, we discussed how to determine how many people drink pumpkin spice lattes in a given time period without learning their identifying information. But say, for example, you would...
Donald J. Wheeler's picture
Donald J. Wheeler
In my article, “Tightened 100% Inspection” (Quality Digest, March 29, 2021), we found that the excess costs associated with tightened specification limits are generally prohibitive. Here we...
David Darais's picture
David Darais
How many people drink pumpkin spice lattes in October, and how would you calculate this without learning specifically who is drinking them, and who is not? Although they seem simple or trivial,...
Donald J. Wheeler's picture
Donald J. Wheeler
Inspection sounds simple. Screen out the bad stuff and ship the good stuff. However, measurement error will always create problems of misclassification where good stuff is rejected, and bad stuff...
Scott A. Hindle's picture
Scott A. Hindle
A quick Google search returns many instances of the saying, “A man with a watch knows what time it is. A man with two watches is never sure.” The doubt implied by this saying extends to manufacturing...
William A. Levinson's picture
William A. Levinson
Traditional statistical methods for computing the process performance index (Ppk) and control limits for process-control purposes assume that measurements are available for all items or parts. If,...
Fred Schenkelberg's picture
Fred Schenkelberg
There is a type of error that occurs when conducting statistical testing: to work very hard to correctly answer the wrong question. This error occurs during the formation of the experiment. Despite...
Adam Conner-Simons's picture
Adam Conner-Simons
This story was originally published by MIT Computer Science & Artificial Intelligence Lab (CSAIL). Scatterplots. You may not know them by name, but if you spend more than 10 minutes online, you’...
Jay Arthur—The KnowWare Man's picture
Jay Arthur—The KnowWare Man
There are two ways to increase profits: increase sales or reduce costs. Although most data analysis seeks to find more ways to sell more stuff to more people, addressing preventable problems is an...
Matthew Bundy's picture
Matthew Bundy
Untitled Document Burning plastic cart carrying a fax machine, a laptop computer, and a three-ring binder. Click here for larger image. Credit: FCD/NIST Several centuries ago, scientists...
Douglas Allen's picture
Douglas Allen
Any number derived from real observation is made up of three components. The first of these is the intended signal, the “perfect” value from the object being observed. The second is error (or noise)...
Donald J. Wheeler's picture
Donald J. Wheeler
In part one we found the baseline portion of an XmR chart to be the best technique for identifying potential outliers among four tests with variable overall alpha levels. In this part we will look at...
Anthony D. Burns's picture
Anthony D. Burns
Augmented reality (AR) means adding objects, animations, or information, that don’t really exist, to the real world. The idea is that the real world is augmented (or overlaid) with computer-generated...
Donald J. Wheeler's picture
Donald J. Wheeler
The first statistical test was a test for outliers. The problem of what to do about outliers has been around from the beginnings of data analysis. Part one will compare four tests for outliers. Next...
Donald J. Wheeler's picture
Donald J. Wheeler
Every introductory class in statistics teaches how to obtain a global standard deviation statistic. While this descriptive statistic characterizes the dispersion of the data, it is not the correct...
Donald J. Wheeler's picture
Donald J. Wheeler
On Sept. 29, 2020, the recorded worldwide death toll from Covid-19 reached 1 million. Six days earlier the United States reached 200,000 Covid-related deaths. So how did the United States with only 4...
Eric Weisbrod's picture
Eric Weisbrod
The idea of digital transformation can be scary. The growth of technology is outpacing a comfortable pace of adoption for many manufacturers. But remaining content with the status quo often means...
Steve Wise's picture
Steve Wise
The importance of data analysis in manufacturing operations can’t be overstated. Over the years, manufacturers have used statistical process control (SPC) methods and tools to study historical data...