Friday, June 30, 2023

Mind games of measurements and estimates: Hidden meanings behind numbers and units

I'm a fan of science and nature documentaries. A few years ago, National Geographic Abu Dhabi was my favorite channel. It primarily featured original NatGeo content, which was dubbed in Arabic.
The content variety and interesting topics from construction, to wild life, air crash investigations and even UFO; provided me with a stream of knowledge and enjoyment. But in some times, also confusion!

One source of confusion was the highly accurate numbers used to describe things that normally could not be measured to that level of accuracy!
In one instance, a wild animal was described to have a weight reaching something like 952 kilograms. Not 900, not 1000 or even 950, but exactly 952.
In another instance, a man was describing a flying object, and he mentioned that the altitude of that object was 91 meters. That man must have laser distance meters in his eyes!

When I thought about this, I figured out that probably while translating these episodes, units of measurements were converted from pounds to kilograms, from feet and yards to meters, and from miles to kilometers, and so on. This is because the metric system is used in the Arab world and is more understandable by the audience.
Converting the above numbers back to the original units made them sound more logical. The wild animal weighed approximately 2200 pounds, and the man was describing an object flying about 100 yards or 300 feet high. That made much more sense.

But why did these round figure numbers seem more logical and more acceptable when talking about things that cannot be accurately measured? After all, 2200 pound are equal to 952 kilograms, and 100 yards are 91.44 meters. Right?

Apparently, the way we perceive numbers in casual conversations implicitly associates an accuracy level.
This Wikipedia note gives an example of this:
"Sometimes, the extra zeros are used for indicating the accuracy of a measurement. For example, "15.00 m" may indicate that the measurement error is less than one centimetre (0.01 m), while "15 m" may mean that the length is roughly fifteen metres and that the error may exceed 10 centimetres."

Similarly, smaller units can be used to give a deceiving indication of accuracy. A few years ago, I was working with a colleague on a high level estimates of a software project. We used weeks as our unit of estimate because -as expected- we knew very little about the project and we expressed this in terms of coarse-grained estimates.
From experience, we knew that this level of accuracy won't be welcome by who requested the estimates, and they may want to get more accurate ones. I laughingly told my colleague: "If they want the estimates in hours, they can multiply these numbers by 40!". I feel I was mean saying that. Of course the point was the accuracy, not the unit conversion.

One nice thing about using Fibonacci numbers in relative estimates, is that they detach the numeric estimates from any perceived accuracy. When the estimate is 13 story points, it's totally clear that the only reason why it's 13, - not 12 or 14  for example- is not because we believe it to be accurately 13. It's just because we don't have the other numbers on the estimation cards. It's simply a best guess.

Beware of the effects of units and numbers you use. They may communicate more than what you originally intended.

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