Statistics Article

William A. Levinson’s picture

By: William A. Levinson

Experiments that might require a handful of real-number measurements (variables data) could need hundreds or more attribute data for comparable power, i.e., the ability to determine whether an experiment improves performance over that of a control. Sample sizes needed for ANSI/ASQ Z1.4 (for inspection by attributes) are similarly much larger than sample sizes for ANSI/ASQ Z1.9 (for inspection by variables).

Inderjit Arora’s picture

By: Inderjit Arora

Objective auditing has always been a challenge, and this is especially true now for ISO 9001:2015 audits. To better meet customer expectations, fundamental changes have been introduced to the standard to address current business realities and advancements in technology. Much of the responsibility of meeting the new requirements falls on leaders, and a careful, objective audit to the standard can help them.

NIST’s picture


NIST scientists have devised and improved a prototype instrument the size of a loaf of bread that can substantially increase the accuracy of length measurements in commerce. Perhaps surprisingly, it does so by achieving the most accurate measure of the refractive index of air reported to date.

TÜV SÜD America’s picture

By: TÜV SÜD America

The revised ISO 9001:2015 standard was published on Sept. 23, 2015. The release of this standard has many organizations preparing for the transition from ISO 9001:2008, and with transition comes uncertainty: How long will it take? What will it cost my organization? Where do I start? These and other questions are far from uncommon.

Fred Schenkelberg’s picture

By: Fred Schenkelberg

The planning of environmental or reliability testing becomes a question of sample size at some point. It’s probably the most common question I hear as a reliability engineer: How many samples do we need?

Douglas C. Fair’s picture

By: Douglas C. Fair

Sponsored Content

Statistical process control (SPC) software has been around for decades, used by manufacturers across industries to help monitor process behavior and control quality on the shop floor. Like any technology, the software has evolved over the years into something much more than a tool for collecting quality data from a single manufacturing site.

Eston Martz’s picture

By: Eston Martz

I read trade publications that cover everything from banking to biotech, looking for interesting perspectives on data analysis and statistics, especially where they pertain to quality improvement.

Eston Martz’s picture

By: Eston Martz

Whatever industry you’re in, you’re going to need to buy supplies. If you’re a printer, you’ll need to purchase inks, various types of printing equipment, and paper. If you’re in manufacturing, you’ll need to obtain parts that you don’t make yourself. But how do you know you’re making the right choice when you have multiple suppliers vying to fulfill your orders? How can you be sure you’re selecting the vendor with the highest quality, or eliminating the supplier whose products aren’t meeting your expectations?

Scott A. Hindle’s picture

By: Scott A. Hindle

When considering how good a production process is, it’s important to ask, “Can we expect the output to be fully conforming?” An assessment of process capability can answer this. Data are needed, but how many? Is “30” the right number? This article examines these last two questions.

Douglas Allen’s picture

By: Douglas Allen

It’s a cold winter’s night in northern New Hampshire. You go out to the woodshed to grab a couple more logs, but as you approach, your hear a rustling inside the shed. You’ve gotten close enough to know you have a critter in the woodpile. You run back inside, bolt the door, hunker down with your .30–06, and prepare for a cold, fireless night.

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