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Pay Clerk Production Woes

Pay Clerk Production Woes
A company was having quality control problems. Friday morning was when the problems happened, but why just on Fridays?
Mysteries of Science


This story comes from a mathematics professor who does consulting in Binghamton, New York. A client was having quality control problems and things didn't exactly add up.

Production yields were high most of the time, but they would periodically drop to almost zero for a very short time and then zoom back up again. The problem occurred almost every week, and in several locations, but not exactly at the same time.

A few problems would also show up a day or two later, but it was always a spike of short duration on the quality curve. It seemed like a single factor was causing the problems. The professor started analyzing data by plotting yield quality vs. time.

The data was not random and fit a very tight pattern. What made it seem complex at first was that a defect produced in one department did not show up as bad product until it went through more steps a few days later.

For example, raw material produced in department "A" could have a hidden defect that would not be picked up for several days until it went through the final step in department "C" where quality was more carefully checked, or where the process exaggerated the defect. The professor graphed the data to present a visual story. The time plot of defects by department was dramatic when viewed together. He came to the irrefutable conclusion that Friday morning was the source of all the problems, even those that occurred on the following Monday.

The data was consistent for ten consecutive Fridays. As near as he could pinpoint the trouble, something odd was happening between 11:00 AM and  noon on Fridays. It was time for action. It was time to camp out and visit the factory.

Here's the rest of the story.

The professor sat down at an obscure desk in a location where he was sure the quality-demolishing event was occurring. That morning, a young lady from the same university, a part-time intern, came by to hand out paychecks.

She was very attractive, to put it mildly. As she walked through each workspace men, young and old, stopped to gawk and chat for a few "harmless" minutes. Heck, it was Friday, and this was the perk that came with their paycheck, the most fun you can have in a serious workplace.

The professor had to agree, it was not very easy to concentrate on work for those precious minutes of idle talk. So what was the answer? "Pretty Paycheck Patty" started to deliver checks during break time. This was a classical time-dependency case, but always keep an eye out for the human factor.


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