Let me tell you about something.

Distractions and amusements, with a sandwich and coffee.

Twenty — minutes — maybe — more.
•
• choose four words

Typography geek? If you like the geometry and mathematics of these posters, you may enjoy something more lettered. Visions of type: Type Peep Show: The Private Curves of Letters posters.

numbers.tgz

1,000,000 digits of π, φ, e and ASN.

Watch the video at Numberphile about my art.

Explore Pi Day art for 2014.

All the artwork can be purchased from Fine Art America.

Proclus got it right when he said (as quoted by M. Kline in *Mathematical Thought from Ancient to Modern Times*)

Wherever there is number, there is beauty.

So let's explore what Pi looks like with something whimsical and pretty and colourful. Rational art of the highly irrational, a regime where beauty runs with her hair down and lets her "*ribbons to flow confusedly.*" Robert Herrick says it well in Sweet Disorder,

I see a wild civility;—

Do more bewitch me, than when art

Is too precise in every part.

The posters explore the relationship between adjacent digits in Pi, which are encoded by color using the scheme shown above. The design appears to shimmer due to the luminance effect. In some versions of the poster, adjacent identical (or similar) digits are connected by lines.

Want more math + art? Discover the Accidental Similarity Number and other number art. Find humor in my poster of the first 2,000 4s of Pi.

The recipe for each poster is included and gives the color of the *i*th outer/inner circle. π[i] is used to represent the *i*th digit of π. For example, the recipe

π[i] / π[i+1]

generates a poster whose outer circle color encodes the *i*th digit and the inner circle color encodes the next digit (*i*+1). In this scheme, inner and outer circles of adjacent positions have the same color.

The posters were generated automatically with a Perl script that generated SVG files. Post processing and layout was done in Illustrator. If you are interested in depicting your favourite number this way, let me know.

The design was inspired by the beautiful AIDS posters by Elena Miska.

I calculated Pi to 13,099,586 digits and then I found love.

It's fun to look for words in Pi. I wanted to know the first time that *love* appears in Pi. When encoded using the scheme a=0, b=1, ..., z=25, *love* is the digit 1114214. This digit appears first at position 13,099,586 (...8921991631**1114214**8187311392...). And, of course, infinitely many times after that.

If you use the scheme a=1, b=2, ..., z=26, then *love* becomes 1215225. This is first seen at 6,317,696 (...6103119129**1215225**6606850141...).

Because the digits of Pi never repeat and are distributed randomly (as far as we know), if you look long enough you'll find all the words in Pi infinitely many times.

π[i] / grey, 80% opacity

π[i] / π[i+1], 80% opacity

π[i] / grey, 80% opacity (equal neighbours connected)

π[i] / π[i+1], 80% opacity (equal neighbours connected)

— / π[i+1] (equal neighbours connected, unconnected digits not shown)

π[i] / π[i+1] (equal neighbours connected with line width proportional to difference in neighbour digits *d*∈{0,1,2}, unconnected digits not shown)

π[i] / π[i+1] (equal neighbours connected with line width proportional to difference in neighbour digits *d*∈{0..5}, unconnected digits not shown)

Pi (π): — / red (equal neighbours connected, unconnected digits not shown)

Phi (φ): — / white (equal neighbours connected, unconnected digits not shown)

e: — / grey (equal neighbours connected, unconnected digits not shown)

π[i] / grey, 80% opacity (equal neighbours connected)

π[i] / π[i+1], 80% opacity (equal neighbours connected)

π[i] / π[i+1] &>

π[i] / grey, 80% opacity (equal neighbours connected, unconnected digits not shown)

π[i] / π[i+1], 80% opacity (equal neighbours connected, unconnected digits not shown)

The split plot design originated in agriculture, where applying some factors on a small scale is more difficult than others. For example, it's harder to cost-effectively irrigate a small piece of land than a large one. These differences are also present in biological experiments. For example, temperature and housing conditions are easier to vary for groups of animals than for individuals.

The split plot design is an expansion on the concept of blocking—all split plot designs include at least one randomized complete block design. The split plot design is also useful for cases where one wants to increase the sensitivity in one factor (sub-plot) more than another (whole plot).

Altman, N. & Krzywinski, M. (2015) Points of Significance: Split Plot Design *Nature Methods* **12**:165-166.

1. Krzywinski, M. & Altman, N. (2014) Points of Significance: Designing Comparative Experiments *Nature Methods* **11**:597-598.

2. Krzywinski, M. & Altman, N. (2014) Points of Significance: Analysis of variance (ANOVA) and blocking *Nature Methods* **11**:699-700.

3. Blainey, P., Krzywinski, M. & Altman, N. (2014) Points of Significance: Replication *Nature Methods* **11**:879-880.

In an audience of 8 men and 8 women, chances are 50% that at least one has some degree of color blindness^{1}. When encoding information or designing content, use colors that is color-blind safe.

Nature Methods has announced the launch of a new statistics collection for biologists.

As part of that collection, announced that the entire Points of Significance collection is now open access.

This is great news for educators—the column can now be freely distributed in classrooms.

I've posted a writeup about the design and redesign process behind the figures in our Nature Methods Points of Significance column.

I have selected several figures from our past columns and show how they evolved from their draft to published versions.

Clarity, concision and space constraints—we have only 3.4" of horizontal space— all have to be balanced for a figure to be effective.

It's nearly impossible to find case studies of scientific articles (or figures) through the editing and review process. Nobody wants to show their drafts. With this writeup I hope to add to this space and encourage others to reveal their process. Students love this. See whether you agree with my decisions!

Past columns have described experimental designs that mitigate the effect of variation: random assignment, blocking and replication.

The goal of these designs is to observe a reproducible effect that can be due only to the treatment, avoiding confounding and bias. Simultaneously, to sample enough variability to estimate how much we expect the effect to differ if the measurements are repeated with similar but not identical samples (replicates).

We need to distinguish between sources of variation that are nuisance factors in our goal to measure mean biological effects from those that are required to assess how much effects vary in the population.

Altman, N. & Krzywinski, M. (2014) Points of Significance: Two Factor Designs *Nature Methods* **11**:5-6.

1. Krzywinski, M. & Altman, N. (2014) Points of Significance: Designing Comparative Experiments *Nature Methods* **11**:597-598.

2. Krzywinski, M. & Altman, N. (2014) Points of Significance: Analysis of variance (ANOVA) and blocking *Nature Methods* **11**:699-700.

3. Blainey, P., Krzywinski, M. & Altman, N. (2014) Points of Significance: Replication *Nature Methods* **11**:879-880.

We've previously written about how to analyze the impact of one variable in our ANOVA column. Complex biological systems are rarely so obliging—multiple experimental factors interact and producing effects.

ANOVA is a natural way to analyze multiple factors. It can incorporate the possibility that the factors interact—the effect of one factor depends on the level of another factor. For example, the potency of a drug may depend on the subject's diet.

We can increase the power of the analysis by allowing for interaction, as well as by blocking.

Krzywinski, M., Altman, (2014) Points of Significance: Two Factor Designs *Nature Methods* **11**:1187-1188.

Blainey, P., Krzywinski, M. & Altman, N. (2014) Points of Significance: Replication *Nature Methods* **11**:879-880.

Krzywinski, M. & Altman, N. (2014) Points of Significance: Analysis of variance (ANOVA) and blocking *Nature Methods* **11**:699-700.

Krzywinski, M. & Altman, N. (2014) Points of Significance: Designing Comparative Experiments *Nature Methods* **11**:597-598.