Bill had a problem. His company's baseball team wasn't doing that well, and he was part of the reason. Bill was
in a long slump. Frankly, he stunk at the plate. But Bill is a Six Sigma Black Belt. He decided to approach his batting problem just like he would approach any process
problem at work--by conducting a designed experiment. First, Bill determined which factors are important. He wrote up a lengthy list and then winnowed it down to four experimental variables (see
Table 1). Table 1: Experimental Variables for Hitting
Bill decided to spend a few evenings and weekends on the practice field
swinging at 100 pitches for each of the 16 combinations of the four variables needed to conduct a full-factorial experiment. The field was equipped with a
pitching machine that could be programmed to throw pitches at either 60 mph or 80 mph. Bill decided to count any ball that went past the infield in fair
territory as a hit. Over a two-week period Bill was able to complete the experiment, producing the results shown in Table 2.
Table 2: Bill's Batting Experiment
The analysis indicates that factors B and D, and especially the C-D interaction,
make big differences in Bill's performance. Factors A and C do not have a significant effect on Bill's batting average. The analysis in Table 3 shows the details. Table 3: Significant Factor Effects
The 95-percent confidence interval for C (position in the batter's box) includes
zero, meaning that C is not statistically significant as a main effect. (C is included because the significant C-D interaction term requires it for statistical
reasons.) However, the other factors in the table--B (choke on the bat) and D (speed of the pitch)--are statistically significant. The most important factor is
the C-D interaction, which has an impressive effect of more than 9 percent. The coefficient estimate tells us what happens to Bill's batting average as we go
from one level of the variable to another. For example, when B is at the high level (choke up on the bat two inches), Bill's batting average improves by about four percentage points. The analysis indicates that when Bill is facing a pitcher with real heat (80 mph isn't too bad for an amateur pitcher), he can improve his batting average from 8
percent to 28.75 percent by standing near the back of the batter's box (see Table 4). Conversely, when Bill is up against a 60-mph hurler, he's better off in
the front of the batter's box (38.75 percent in front hits vs. 15 percent in back). Combining all of these results, Bill's strategy is to always choke up on the bat
and position himself in the batter's box depending on the expected speed of the pitch. Table 4: Bill's Results
Bill may not be ready for the majors with this strategy, but he's hitting a lot
better than the .206 (20.6%) he'd been getting without a strategy. In the meantime, Bill, work on hitting that fast ball! About the author Thomas Pyzdek is an Arizona Diamondbacks fan and a consultant in Six
Sigma. He has written more than 50 books, software and training products, including The Complete Guide to Six Sigma (www.qualityamerica.com ).
Pyzdek served on the first board of examiners for the Malcolm Baldrige National Quality Award. He is a fellow of the American Society for
Quality, an ASQ-certified quality and reliability engineer, and a recipient of the ASQ Edwards Medal. Pyzdek is also the President of the International Quality Federation (www.iqfnet.org ). E-mail him at Tom Pyzdek . |
