in which I use science in my daily life

The wifely one and I are roughly the same height.  Aside from making our cycling tours more flexible, it also brings up some questions:

If people change height during the course of the day, are there any points in time where she is taller than I am?  After some rounds of “I don’t think so” and “well, it sure looked like it”, we decided to answer the question with… science!  Because we’re both sciency people, and it was something we could actually set up an experiment to do.

For two weeks, when we got up, we measured each other (barefoot) against a wall in the apartment.  Just before bed, we did the same thing again.  Over 14 days we did this; with the addition of a few times I tried to measure myself when I got up (about an hour earlier) to see if it made a difference (inconclusive even by my vague standards).  Each measurement was written down on a post-it note on the wall, forming a visual record.

Each measurement was not terribly accurate.  While we have a level, and a selection of hardcover books, we usually just measured with the measuring tape, as level as possible, up against the wall.  In addition, we’re both close to the same height, so the tops of each others’ heads weren’t exactly the easiest things to see.  Against that, there were 28 different measurements of each of us at two times of day, and while it was the same person measuring the same other person every time, I think it’s reasonable to expect a bias toward measuring too high or too low to change at some point during two weeks.  Although, there WAS a confirmation bias inherent in having all the previous post-it notes on the wall with our other measurements… Actually, now that I think about it, there are many things I would change about the experimental design if I knew I would be writing about it on this blog.

Anyway, the results were these:

Yes, I used LibreOffice to analyze the data.

My height is 68.4 +/- 0.5 inches (yes, I used inches.  Shut up); her height is 67.6 +/- 0.6 inches.  If you want to break that up into morning-evening, my height in the morning is 68.7 +/- 0.5 and in the evening, it’s 68.1 +/- 0.3.  Her height is 68.1 +/- 0.3 in the morning, and 67.0 +/- 0.2 in the evening.

From this we can draw some conclusions: Given the errors, it’s not clear that I change height over the course of the day, but it is far more likely (2-sigma) that my wife gets shorter throughout the course of the day.  Actually, we did once measure her being taller than me, if you check the table.  (So: yes, she was right, she is occasionally taller than me.)

Why bother doing this?  Because we can. Because with science you actually CAN answer these little dinner-party-trivia questions.  Because the next time someone asks me my height, I can give them uncertainties.   Even though it’s not particularly rigorous, it’s a good home-game experiment demonstrating how, in science, you have to pay attention to all the data.  You can do it yourself: Does the elevator always stop on the fourth floor whenever I get on?  Do I always end up sitting at that traffic light for two minutes?  Does it never rain when I bring my umbrella?  Is it really faster to get to work if I avoid the expressway? (remember, science can be useful in your daily life!)

As for myself and the wifely one?  Our next experiment will be to determine if the reddest and bluest wavelengths our eyes can see are the same.  Because we can.  It should be fun!

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