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Distractions and amusements, with a sandwich and coffee.

listen; there's a hell of a good universe next door: let's go.
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On March 14th celebrate `\pi` Day. Hug `\pi`—find a way to do it.

For those who favour `\tau=2\pi` will have to postpone celebrations until July 26th. That's what you get for thinking that `\pi` is wrong. I sympathize with this position and have `\tau` day art too!

If you're not into details, you may opt to party on July 22nd, which is `\pi` approximation day (`\pi` ≈ 22/7). It's 20% more accurate that the official `\pi` day!

Finally, if you believe that `\pi = 3`, you should read why `\pi` is not equal to 3.

Not a circle in sight in the 2015 `\pi` day art. Try to figure out how up to 612,330 digits are encoded before reading about the method. `\pi`'s transcendental friends `\phi` and `e` are there too—golden and natural. Get it?

This year's `\pi` day is particularly special. The digits of time specify a precise time if the date is encoded in North American day-month-year convention: 3-14-15 9:26:53.

The art has been featured in Ana Swanson's Wonkblog article at the Washington Post—10 Stunning Images Show The Beauty Hidden in `\pi`.

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I find this image deeply beautiful and deeply troubling, and I’ll try to explain why. —Max Cooper

The 7-level tree map was used for the Transcendental Tree Map track on Max Cooper's Yearning for the Infinite album. The album is an “audio/visual rendering with our obsession with the unobtainable” .

The video for the track was a collaboration between myself and Nick Cobby. The music contains layered loops whose lengths are based on prime numbers—as the track plays, some loops individually come in and out of phase with others, forming a longer loop. The full set never synchronizes though.

The transcendental tree map encodes the first 20,244 digits of `\pi` = 3.1415...7012.

The video constructs and then chaotically deconstructs a 7 level tree map of the digits of `\pi`. This map is shown below and is similar to other images I made for 2015 Pi Day, except that here the map is formatted for a 16:9 screen.

The video starts with an explicit construction of the map. This process begins with dividing the canvas with 3 vertical lines, which forms 4 rectangles. Each of the four rectangles formed by this process is divided with 1, 4, 1 and 5 horizontal lines, respectively. This forms 2 + 5 + 2 + 6 = 15 rectangles. Each of the 15 rectangles is divided by vertical lines according to the next 15 digits of Pi. This process repeats until we have performed the loop 7 times.

The division of each rectangle is not even—the positions of the lines are slightly jittered. This gives the map a more organic feel.

The number of digits encoded in each loop is 1, 4, 15, 98, 548, 2,962 and 16,616. In total, 17,180 vertical and 3,064 horizontal lines are drawn and these form the backbone of the map.

The video is created by layering numerous animations of the construction of the map, in which the rate and order of line growth is varied. Blinking rectangles indicate that the lines for a digit have completed drawing.

The Sanctuary Project is a Lunar vault of science and art. It includes two fully sequenced human genomes, sequenced and assembled by us at Canada's Michael Smith Genome Sciences Centre.

The first disc includes a song composed by Flunk for the (eventual) trip to the Moon.

But how do you send sound to space? I describe the inspiration, process and art behind the work.

A forest of digits

Celebrate `\pi` Day (March 14th) and finally see the digits through the forest.

This year is full of botanical whimsy. A Lindenmayer system forest – deterministic but always changing. Feel free to stop and pick the flowers from the ground.

And things can get crazy in the forest.

Check out art from previous years: 2013 `\pi` Day and 2014 `\pi` Day, 2015 `\pi` Day, 2016 `\pi` Day, 2017 `\pi` Day, 2018 `\pi` Day and 2019 `\pi` Day.

*All that glitters is not gold. —W. Shakespeare*

The sensitivity and specificity of a test do not necessarily correspond to its error rate. This becomes critically important when testing for a rare condition — a test with 99% sensitivity and specificity has an even chance of being wrong when the condition prevalence is 1%.

We discuss the positive predictive value (PPV) and how practices such as screen can increase it.

Altman, N. & Krzywinski, M. (2021) Points of significance: Testing for rare conditions. *Nature Methods* **18**:224–225.

*We demand rigidly defined areas of doubt and uncertainty! —D. Adams*

A popular notion about experiments is that it's good to keep variability in subjects low to limit the influence of confounding factors. This is called standardization.

Unfortunately, although standardization increases power, it can induce unrealistically low variability and lead to results that do not generalize to the population of interest. And, in fact, may be irreproducible.

Not paying attention to these details and thinking (or hoping) that standardization is always good is the "standardization fallacy". In this column, we look at how standardization can be balanced with heterogenization to avoid this thorny issue.

Voelkl, B., Würbel, H., Krzywinski, M. & Altman, N. (2021) Points of significance: Standardization fallacy. *Nature Methods* **18**:5–6.

*Clear, concise, legible and compelling.*

Making a scientific graphical abstract? Refer to my practical design guidelines and redesign examples to improve organization, design and clarity of your graphical abstracts.

An in-depth look at my process of reacting to a bad figure — how I design a poster and tell data stories.