On March 14th celebrate `\pi` Day. Hug `\pi`—find a way to do it.
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.
Caelum non animum mutant qui trans mare currunt.
This year: creatures that don't exist, but once did, in the skies.
And a poem.
This year's `\pi` day song is Exploration by Karminsky Experience Inc. Why? Because "you never know what you'll find on an exploration".
The `\pi` star chart has 80 constellations. Many of them have stories to tell—look up and listen.
I would love to have a complete mythology for each constellation. Please submit your stories!
Camptor — Veronica Falconeri
The symbols beside the constellation index indicate which hemisphere the constellation can be found (◓ north, ◒ south or ● both). The first 25 brightest stars in the constellation are also listed, along with their apparent magnitude, longitude and latitude.
Alaotra is frustrated that Tadorna seems to get all the attention. Often confused for a duck, Alaotra would love you to know that she's in fact a grebe. She's very proud of this fact, despite of being prone to falls due to some biomechanical issues having to do with foot placement.
Shape: 3/57 stars, 3 edges.
Shape: 4/42 stars, 4 edges.
Shape: 2/21 stars, 1 edges.
Araucaria is truly a marvel. She is so large, in fact, that the constellation only shows the canopy and does not include the tree trunk—which was known to reach a height of 100 m. Araucaria offers plenty of protection and has many flying friends all around, including Urania, Moho and WhĒkau. Just a little further are the ducks (and a grebe), Camptor, Mariana, Tadorna and Alaotra. They would love to visit Araucaria but worry that they are too heavy to perch on her branches.
Shape: 8/1232 stars, 8 edges.
Shape: 7/1838 stars, 7 edges.
Shape: 5/1019 stars, 4 edges.
Shape: 14/2287 stars, 14 edges.
Urged by Camelops, Ardea is trying to beat Aepyornis and be the first to see beyond the sky. It looks like she may be winning, but Camelops knows its a futile pursuit. Only he knows what is beyond the sky.
Shape: 9/1768 stars, 9 edges.
Argentavis is a big bird in the big sky. There are many stories of his feud with Pelagornis, who spreads his wings in the southern hemisphere — both insist that they have the biggest wing span.
Shape: 5/69 stars, 4 edges.
Runs in the vast plains of the north together with Mammuthus and Quagga.
Shape: 7/62 stars, 7 edges.
The king lizard dives into the depths of the sky at the very tip of the south hemisphere. Some say that he is chasing the South star, `\alpha` Basilosaurus.
Shape: 3/61 stars, 2 edges.
Shape: 5/602 stars, 5 edges.
It's hard to be bigger than Bron. He must always pay attention not to step on his frolicking friend Compsognathus, who seeks to find protection in Bron's shadow. Some believe that if Bron stretches his neck, he can look above the sky! But don't tell Ardea this—she's in a contest with Aepyornis to be the first!
Shape: 12/5230 stars, 11 edges.
Camelops played a cruel joke on Ardea and Aepyornis, asking them to try to look beyond the sky. Both think they have the longest neck, so they're still trying!
Shape: 6/1789 stars, 5 edges.
Camptor flew long and far to find a pond without ducks on Earth, but could find no such pond. So she chose longest journey, and flew to settle in the sky.
Shape: 3/570 stars, 3 edges.
Shape: 4/7 stars, 4 edges.
The last elk was shot in Pennsylvania. Oops.
Shape: 6/296 stars, 5 edges.
The tiniest of dinosaurs, Compsognathus hides in the protection of Bron's shadow.
Shape: 2/190 stars, 1 edges.
Shape: 5/364 stars, 5 edges.
Shape: 6/57 stars, 5 edges.
Shape: 3/82 stars, 2 edges.
Shape: 4/1164 stars, 3 edges.
Ever since meeting Pinta, they've been fast (and slow) friends.
Shape: 4/233 stars, 4 edges.
Shape: 5/47 stars, 5 edges.
It is thought that each night Desmodus flies up against the dome of the sky, looking for a way to escape.
Shape: 3/122 stars, 3 edges.
The last pidgeon, Martha, died in 1914 at the Cincinanati zoo. What a place to leave the earth from, eh?
Shape: 3/33 stars, 3 edges.
The Glyptodon is very slowly crossing from the south to the north hemisphere to play with Bron and Compsognathus. Will he make it?
Shape: 7/332 stars, 7 edges.
Shape: 7/437 stars, 7 edges.
Shape: 3/73 stars, 3 edges.
Shape: 3/53 stars, 3 edges.
Shape: 4/72 stars, 3 edges.
Shape: 6/817 stars, 6 edges.
Toads are studied by herpetologists. I'd love to be one just so that I can say that word at a party.
Shape: 4/106 stars, 4 edges.
Shape: 5/48 stars, 4 edges.
Shape: 8/2155 stars, 7 edges.
Shape: 5/714 stars, 5 edges.
Shape: 6/1028 stars, 6 edges.
Not much is known about when Malpaisomys became extinct. Some think it's when humans and dogs arrived on the Canary islands. Malpaisomys worries that because of his small size, nobody cares.
Shape: 3/38 stars, 3 edges.
Shape: 8/69 stars, 7 edges.
Shape: 3/17 stars, 3 edges.
One word: terrifying. More words: endlessly chasing Tecopa. The megalodon possesses the brightest star in the sky.
Shape: 4/20 stars, 4 edges.
Shape: 5/122 stars, 5 edges.
The Minmi is actually much larger than his name suggests. He really wants you to know that.
Shape: 5/749 stars, 4 edges.
Shape: 5/60 stars, 5 edges.
The ʻōʻō has all its letters with diacriticals. This makes the whēkau jealous. They haven't talked since.
Shape: 6/70 stars, 6 edges.
I frankly hate olives and there's no end to my pleasure in throwing olives at the sky.
Shape: 4/784 stars, 4 edges.
Like Pipilo, the O'ahu 'akepa is the only other multi-part constellation. Here, a pair of akepas are chatting and spreading rumors about Tadorna.
Shape: 4/30 stars, 2 edges.
Rumor has it Palaeoaldrovanda was related to the carnivorous plant genus Aldrovanda! Xerces is seen flying nearby. He must be careful.
Shape: 3/121 stars, 3 edges.
The mayfly loves to pester Raphus, the Dodo bird. He is too worried about guarding his eggs to pay attention to Pecatonica, though.
Shape: 4/58 stars, 3 edges.
He can barely fit in the southern skies. With a wingspan of over 5 meters, he is certain that he is the biggest bird in the sky. However, Argentavis of the northern hemisphere disagrees.
Shape: 6/192 stars, 5 edges.
The Phelsuma was described as unafraid of humans and said to be tame and happy to eat fruit from your hand. Lessons to be learned here?
Shape: 10/131 stars, 10 edges.
Shape: 3/88 stars, 2 edges.
The last of its kind, a male named Lonesome George, died in 2012.
Shape: 5/402 stars, 5 edges.
A rare flocking constellation. These towhees cross hemispheres and keep the Glyptodon company.
Shape: 44/261 stars, 22 edges.
Shape: 5/406 stars, 5 edges.
Shape: 4/652 stars, 4 edges.
The last sighting of a pair of po'ouli was in 2004 and now again, in the sky of pi.
Shape: 4/145 stars, 4 edges.
Tiny guys in the corner.
Shape: 2/7 stars, 1 edges.
Shape: 9/1676 stars, 8 edges.
Comical and uncertain of its stripes, Quagga is often seen asking Aurochs for his advice.
Shape: 6/139 stars, 6 edges.
Raphus is guarding his eggs—the clusters of stars just south of β Raphus (the second brightest star in the constellation) while pestered by Pecatonica.
Shape: 5/358 stars, 5 edges.
Shape: 3/12 stars, 3 edges.
Fleeing from the giant Megalodon, Rodhocetus was an early whale that possessed land mammal characteristics. Some say that he managed to escape from Megalodon and lived out his life on the land, never returning to the sea.
Shape: 6/44 stars, 5 edges.
The last known stalk was given to Emperor Nero. As stories, some have said that he used Silphium as kindle to a larger fire.
Shape: 3/8 stars, 3 edges.
Shape: 5/577 stars, 4 edges.
Shape: 6/202 stars, 6 edges.
Swamphen is delighted to have a diacritical mark in its name, a characteristic shared only by the whēkau, who resides in the northern hemisphere and the ʻōʻō (Moho braccatus) who lives just to the north.
Shape: 3/19 stars, 2 edges.
Rumor has it Tadorna may have snuck into the sky without permission—while not seen since the 1960’s, some say the duck isn’t extinct.
Shape: 3/31 stars, 3 edges.
Tecopa can tolerate heat, which allows him to escape from Megalodon, who will not chase Tecopa through the hot springs.
Shape: 4/100 stars, 3 edges.
The last of its kind was shot by Willem Dafoe in the movie The Hunter. To this day, the Thylacine can be seen screaming in the sky.
Shape: 10/2205 stars, 9 edges.
Shape: 3/481 stars, 3 edges.
Trex is unhappy because he's such a tiny constellation -- he's barely eaten!
Shape: 5/40 stars, 4 edges.
Shape: 6/71 stars, 5 edges.
Shape: 6/751 stars, 5 edges.
Shape: 7/462 stars, 7 edges.
Some members of the genus are not extinct and enjoy being called "corn salad" even though they have never seen a salad.
Shape: 4/1313 stars, 3 edges.
Some say that whēkau can still be heard. Perhaps the joke is on us?
Shape: 3/57 stars, 2 edges.
Brilliant blue butterfly in the dark blue sky. Xerces is the only thing that is bluer than the sky itself. Some say that butterflies are flying flowers and Xerces is never far from Palaeoaldrovanda. He must be careful though. Rumor has it Palaeoaldrovanda was related to the carnivorous plant genus Aldrovanda! Nobody wants to take that chance.
Shape: 8/1299 stars, 8 edges.
Don't let Yersinia's small size fool you. The Black Death may be the smallest creature in the sky, but she'll liquify your insides before you can memorize the 80 constellations. Perhaps out of all the creatures in the sky, this is the one we're happy to see go. But, because it's small, you can never be quite sure Yersinia isn't extinct but merely hiding. Or waiting.
Shape: 3/418 stars, 3 edges.
Quantile regression explores the effect of one or more predictors on quantiles of the response. It can answer questions such as "What is the weight of 90% of individuals of a given height?"
Unlike in traditional mean regression methods, no assumptions about the distribution of the response are required, which makes it practical, robust and amenable to skewed distributions.
Quantile regression is also very useful when extremes are interesting or when the response variance varies with the predictors.
Das, K., Krzywinski, M. & Altman, N. (2019) Points of significance: Quantile regression. Nature Methods 16:451–452.
Altman, N. & Krzywinski, M. (2015) Points of significance: Simple linear regression. Nature Methods 12:999–1000.
Outliers can degrade the fit of linear regression models when the estimation is performed using the ordinary least squares. The impact of outliers can be mitigated with methods that provide robust inference and greater reliability in the presence of anomalous values.
We discuss MM-estimation and show how it can be used to keep your fitting sane and reliable.
Greco, L., Luta, G., Krzywinski, M. & Altman, N. (2019) Points of significance: Analyzing outliers: Robust methods to the rescue. Nature Methods 16:275–276.
Altman, N. & Krzywinski, M. (2016) Points of significance: Analyzing outliers: Influential or nuisance. Nature Methods 13:281–282.
Two-level factorial experiments, in which all combinations of multiple factor levels are used, efficiently estimate factor effects and detect interactions—desirable statistical qualities that can provide deep insight into a system.
They offer two benefits over the widely used one-factor-at-a-time (OFAT) experiments: efficiency and ability to detect interactions.
Since the number of factor combinations can quickly increase, one approach is to model only some of the factorial effects using empirically-validated assumptions of effect sparsity and effect hierarchy. Effect sparsity tells us that in factorial experiments most of the factorial terms are likely to be unimportant. Effect hierarchy tells us that low-order terms (e.g. main effects) tend to be larger than higher-order terms (e.g. two-factor or three-factor interactions).
Smucker, B., Krzywinski, M. & Altman, N. (2019) Points of significance: Two-level factorial experiments Nature Methods 16:211–212.
Krzywinski, M. & Altman, N. (2014) Points of significance: Designing comparative experiments.. Nature Methods 11:597–598.
Celebrate `\pi` Day (March 14th) and set out on an exploration explore accents unknown (to you)!
This year is purely typographical, with something for everyone. Hundreds of digits and hundreds of languages.
A special kids' edition merges math with color and fat fonts.
One moment you're
:) and the next you're
Make sense of it all with my Tree of Emotional life—a hierarchical account of how we feel.