This time the project didn’t start from the data

I have to admit that I didn’t start this project because of the data. It was early 2020, the news about COVID-19 had just begun circulating, but my mind was on a presentation I was supposed to give at the Svelte meetup in Stockholm. Specifically, I needed an example project where lines are animated.

In search of appropriate data, I stumbled upon a recent publication in eLife. It was about human body temperatures across the last decades. The authors came to the conclusion that the human body temperature is decreasing over the years. While the publication uses nice statistical methods to prove this, I was more interested in the unique women and men who took part in the study. What would their personal temperature trajectories look like?

Individual focus

I started R, my data analysis programming language of choice, and loaded the raw data of the paper (open science ftw!). First, I tried to find out how long individual people were followed up in the study. I became quite happy when I saw that some trajectories lasted for several years. I chose those individuals with the longest follow-up time with the intention to plot their body temperatures on one common age scale.

Let the user explore the data

To make it clear that these temperatures come from real humans, I designed clickable human pictograms. A click reveals the respective temperature curve.

Body temperature is complex and unique

While working through the data, I saw that the study authors also noted if a test person had a specific medical condition. I ran a linear regression model on the diagnoses to find out which conditions have the largest effect on body temperature. Not surprisingly, having a cold is somewhat a predictor for a high body temperature. So I put the cold diagnoses as little blue dots into the visualization.

Finally, although I started this project with no data in mind, it gave me new insights in our biology. I realized that there is no standard 37 °C body temperature because each individual has her or his own baseline.