On a Roll: Bowling Balls Follow Four Phases of Motion, Statistical Analysis Reveals

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While assessing a contested regulation, the U.S. Bowling Congress, using Minitab Statistical Software, discovered a previously unknown stage in a ball’s travel down the lane.

A designed experiment and statistical analysis done with Minitab Statistical Software revealed a previously unknown phase of bowling ball motion, giving researchers a new set of questions to pursue—and giving solid evidence that keeping an existing specification would help keep bowling fair.

A designed experiment and statistical analysis done with Minitab Statistical Software revealed a previously unknown phase of bowling ball motion, giving researchers a new set of questions to pursue—and giving solid evidence that keeping an existing specification would help keep bowling fair.

The Minitab analysis showed that a ball's static weight could result in a previously unidentified fourth phase of motion.

When researchers at the U.S. Bowling Congress (USBC) set out to assess a specification for static weight in bowling balls, they didn’t expect to redefine the way balls travel down the bowling lane.

But a designed experiment and statistical analysis done with Minitab Statistical Software revealed a previously unknown phase of bowling ball motion, giving the researchers a new set of questions to pursue—and giving the USBC solid evidence that keeping the specification would help keep bowling fair.

The project is detailed in case studies available from Minitab Inc. and from the U.S. Bowling Congress at their respective Web sites.

Some 70 million Americans take to the lanes each year, making bowling the fifth most popular sport in the United States. More than 2 million people bowl in a U.S. Bowling Congress-certified league, and they take their sport seriously. Many spend in excess of $300 on high-performance bowling balls.

USBC regulations are designed both to keep the game fair and to protect the investment players make in equipment. One such specification concerns “static weight,” which affects the balance of the ball.

After research indicated that static weight showed only a minimal effect on ball motion, many in the bowling community called for increasing the maximum static weight allowance or eliminating the specification altogether.

But changing a regulation is a major decision, so USBC research engineers decided to look more closely at how static weight affects ball motion. They used Minitab to design an efficient experiment, and then to analyze the data they gathered.

Minitab is the leading software for quality improvement and statistics education worldwide. Thousands of companies use Minitab to analyze data for quality improvement programs, and more than 4,000 colleges and universities use it for teaching and research.

The team—led by Nicki Mours, research engineer—worked at the USBC’s International Training and Research Center in Arlington, Texas, which includes specialized equipment including a bowling robot named E.A.R.L. (Enhanced Automated Robotic Launcher) and a highly sophisticated, computer-aided tracking system known as Super CATS.

The team identified six distinct static weight and bowler parameter factors to assess. Testing each factor one-at-a-time would be prohibitively expensive and time-consuming, so the team used Minitab’s Design of Experiment (DOE) capabilities. DOE enables investigators to change multiple factors and then use statistics to determine which have significant effects, reducing the number of runs needed to gather data.

Using Minitab, the team created a six-factor, half-fractional designed experiment with 32 runs, each of which used different combinations of factor settings. Two specially-constructed bowling balls were used for the test runs, one with a symmetrical core and another with an asymmetrical core. Each run was conducted on the same lane, with strict controls to hold ambient temperature, lane surface temperature and room humidity consistent.

When Mours and her team analyzed the data they collected, they got a big surprise.

Previous research had identified three distinct, mathematically predictable phases of bowling ball motion, and static weight appeared to have very little effect on these phases of ball motion. But the Minitab analysis showed that static weight could result in a previously unidentified fourth phase of motion.

To better understand the practical impact of this fourth phase, the researchers did a second experiment to determine if the fourth phase occurred at any of six possible static weights. Using Minitab again, they created a response surface DOE comprising 15 runs. Response surface designs let researchers model curvature in a response, is very useful for seeing how changes in input variables influence a response.

After analyzing the results of the second experiment, Mours and her team concluded that if USBC’s static weight limits were eliminated or increased, parameters could be combined to increase a bowling ball’s entry angle into the pins.

In other words, single-pin or right-side spares could be converted by using a ball with static weight characteristics that redirect the ball toward the pins through no additional skill of bowlers.

In light of this analysis, the USBC retained its specifications for static weight limits in bowling balls. “Our research proved that the current USBC static weight limits are still valid, even in this age of high-tech bowling balls,” says Neil Stremmel, managing director of USBC’s National Governing Body.

Meanwhile, Mours continues to conduct additional research on static weight and many other factors that affect the performance of bowling equipment, and she continues to use Minitab to analyze her data.

The Minitab case study can be found at http://www.minitab.com/uploadedFiles/Company/News/Case_Studies/USBC-EN.pdf, and the USBC report about this project is available at http://usbcongress.http.internapcdn.net/usbcongress/bowl/equipandspecs/pdfs/2011StaticWeightsStudy.pdf

About Minitab

Minitab Inc. is one of the world's leading developers of statistical analysis and process improvement software for academic and commercial users.

Minitab Statistical Software is the preferred data analysis tool for businesses of all sizes and is used in more than 80 countries by thousands of distinguished companies, including Toshiba, DuPont, Boeing, Royal Bank of Scotland, Nestlé and the leading Six Sigma consultants. It has been used to implement virtually every major Six Sigma quality improvement initiative, and to teach statistics in over 4,000 colleges and universities worldwide.

Quality Companion by Minitab is the package professionals use to plan and execute Six Sigma projects in companies around the world, including Xerox, ITT Industries, Providence Health System, Nissan North America, and LexisNexis.

Quality Trainer by Minitab provides easy access to quality statistics expertise whenever you need it. This subscription-based online learning course lets you learn or refresh your knowledge anytime and helps you use Minitab to apply statistics properly. Interactive lessons based on real problems make concepts easy to retain.

Minitab Inc., headquartered in State College, Pa., operates offices in the United Kingdom, France, and Australia, and has additional representatives throughout the world. For more information, visit http://www.minitab.com

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