Spreadsheets R Us

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Once again, it does not surprise me.

My wife has a friend who is married to an engineer. This friend has been wanting a new car for a long time and her husband, an engineer, has been seen as dragging his feet on the issue. This is not the case. Now, I don’t ever want to get into the middle of a marital disagreement, but the fact that her husband is an engineer means a few things.

1. He understands that any present car they have, though over 10 years old, is paid for. It is not costing them monthly payments or a huge chunk of a savings account.

2. Only when the repair rate of the older car reaches that of the rate of all the costs of a new car is it worth buying a new car.

3. New cars cost more in insurance.

4. New cars cost more in registration taxes (if the state has it, ours does).

5. It will take a while to develop the spreadsheet of features, dealers, makes and models, car reviews, mpg rates, repair records, cargo space, safety ratings – to name just a few.
It is this spreadsheet that will take the real time. The old car will rust out faster than it takes to create, test, and tweak this spreadsheet. The old car may break down numerous times before the spreadsheet is complete. But, here is the important thing to remember. Once this spreadsheet is done, the decision will be a well-reasoned one and, geologically speaking, a quick one.

They should have a new car by this time next year. Or the year after.

Thinking Like an Engineer

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There are times that I realize that I not only am an engineer, but I think like one. Case in point: a while ago I lost a few items, all on the same weekend. These were not any of the biggies like a wedding ring or one of our children, but they were things that were inconvenient not to have, used frequently, and cost something to replace. What the items were is not important, so much as the way my mind tried to work the problem. Which should I spend the most effort looking for? Which is of most “value” to me?

While many people think somewhat like this, the engineer will develop a table, or spreadsheet to calculate which item is of the highest value and which he should look for first. I know I did.

The table looked something like the following:


Frequency of Use

Cost to Replace

Likelihood of Finding with Same Effort

Ordinal “Value”




All of the first three columns after the Item column were given a rank of 1 to 10 for each of the items. Then the final column was simply the addition of the three previous values. I could have made it the average, so that the scale was still a 1 to 10 scale. Instead, I played it crazy and the Ordinal “Value” ended up being a 1 to 30 scale. (I can be quite crazy at times.) I also considered but did not pursue the weighting of one factor over another, either by making the scale larger or smaller for a factor (column) or by creating an equation for the Ordinal “Value” that weighted the other three scored values.

Again, these weren’t highly important or expensive items. I think the one that ended with the greatest Ordinal “Value” was my cell phone car charger, being used frequently but not daily, some cost to replace, but more likely to find since it was probably in one of the cars, or not. At any rate, I spent my time looking first for the car charger.

I may have been able to find all three items in the time it took me to derive their Value, but that is not the point, and if you went there before you read this sentence, well, you are likely not an engineer.