Saturday, February 16, 2008

Engineering- Assumptions Can Change Everything

I had an incident with my car yesterday that perfectly illustrated how assumptions can change everything. In engineering, business, mechanics, and many other fields, all data cannot be known so assumptions are often made based on available data. During a case study for one of my final classes at the University of Phoenix, my learning team was involved in designing an information system for a company based on a case study. We decided to use Microsoft Dynamics as a solution. During my part of the weekly paper, I wrote that our team "assumes that this company has a trained and capable IT staff." That information was not present in the case study, yet the development of our business case would have changed if we also had to provide a lot of training, hiring, or even provide the ongoing support ourselves.

Lately my car has been giving off a rattle when I drive. It's been going on for a few weeks and steadily getting worse. By the time I got to work yesterday, it sounded like a diesel. I'm not aware of Suzuki selling a diesel crossover SUV, and I'm sure the regular gas I've been putting in would have killed it. I finally got worried and called Tim, my mechanic. I've been taking my cars to Tim for six years now. It's great having a trustworthy mechanic within walking distance of my house.

Tim listened to my engine. My car is a 2001 with 106000 miles on it. Tim's first suggestion was to take it to a specific Hyundai dealer and buy a Santa Fe. Tim wasn't being cavalier at all. Based on the observable evidence and an assumption I'll get to, he figured I had a valve job that is not worth doing on a car with my mileage.

Then the assumption came into play and he pulled out my dipstick. It was dry. That changed everything. I've been driving my car without oil. Ouch. I guess I should have checked that. I've never noticed an oil leak. Tim and I both assumed that I had oil in my car. It took 5 quarts to fill back up, and the rattle started going away.

On the assumption that I had oil in my engine, the prognosis was very bad. Adding oil began to fix the problem, but now we're left with the question of why all the oil had gone out of my engine in just 4000 miles. I know I'm a little late but my wife tells me money is tight so I was waiting for yesterday's paycheck to do an oil change. I know I should be able to get 4000-5000 miles out of a car without the oil running dry.

I know the common saying goes "When you assume, you make an ass out of U and ME." That is a wise proverb, yet not always accurate. We make assumptions every day. We probably couldn't make the simplest decision without making an assumption. But like in a business case, make sure those assumptions are based on as much available information as possible. Make the assumptions bridge a gap between information that you actually have. Be ready to change your assumptions with new information.

Now we wait until Monday when Tim can search for the oil leak. The final assumption I will make in this blog post is that since Tim did my last oil change, it was done right and my oil is leaving my engine another way.

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