resources
visualizations
presentations
lunch break
Distractions and amusements, with a sandwich and coffee.
data visualization + art
The data will stand out—and you will too.
BD Genomics stereoscopic art exhibit — AGBT 2017
Art is science in love.
— E.F. Weisslitz
data in new dimensions
convergence of art, genomics and bioinformatics
In genomics, insights can hinge on a difference of one. One cellular mutation to go from healthy to diseased. One cell migration from tumor to metastasis. Even subtle differences in gene expression between healthy cells shapes their form and function.
In Data in New Dimensions, we’ve created an immersive data art experience celebrating the individuality and often underestimated influence of the single cell—captured by high-throughput single cell analysis.
Using the rich data from the very tools and instruments in this room, we’ve transformed data points back into cells and, informed by their differences, allowed those cells to once again rejoin the world of the viewer in the third dimension.
How do these canvases make you think about the difference of one in your work?
difference of one expression
This piece contrasts two different blood cell states, diseased versus healthy, in such a way that the differences manifest as depth. Cells on the base plane (the closest to the wall) represent healthy control cells, while diseased cells ascend increasingly closer to the viewer based on how different they are from their healthy counterpart.
difference of one migration
This piece paints a picture of the diversity of disease, showing how the cells of a tumor and its metastasis vary in expression patterns. These differences are manifested in the piece through each cell’s position in the third dimension. Cells from the primary tumor exist on the base layer (closest to the wall). Cells from the metastatic site project into the room based on the degree of difference from the nearest primary tumor cell in their cluster.
difference of one function
This piece explores the expression differences that help determine a healthy cell’s role within an organism. Each cluster corresponds to a different cell type along the renal tubule, with that cluster’s depth mapping to its position along the tubule. Blood enters the tubule through the cells on the base layer (closest to the wall) and is filtered by the cells in the successively ascending layers. The remaining waste exits past the cells in the layer nearest to the viewer.
news + thoughts
Markov Chains
You can look back there to explain things,
but the explanation disappears.
You'll never find it there.
Things are not explained by the past.
They're explained by what happens now.
—Alan Watts
A Markov chain is a probabilistic model that is used to model how a system changes over time as a series of transitions between states. Each transition is assigned a probability that defines the chance of the system changing from one state to another.
Together with the states, these transitions probabilities define a stochastic model with the Markov property: transition probabilities only depend on the current state—the future is independent of the past if the present is known.
Once the transition probabilities are defined in matrix form, it is easy to predict the distribution of future states of the system. We cover concepts of aperiodicity, irreducibility, limiting and stationary distributions and absorption.
This column is the first part of a series and pairs particularly well with Alan Watts and Blond:ish.
Grewal, J., Krzywinski, M. & Altman, N. (2019) Points of significance: Markov Chains. Nature Methods 16:663–664.
1-bit zoomable gigapixel maps of Moon, Solar System and Sky
Places to go and nobody to see.
Exquisitely detailed maps of places on the Moon, comets and asteroids in the Solar System and stars, deep-sky objects and exoplanets in the northern and southern sky. All maps are zoomable.
Quantile regression
Quantile regression robustly estimates the typical and extreme values of a response.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.
Background reading
Altman, N. & Krzywinski, M. (2015) Points of significance: Simple linear regression. Nature Methods 12:999–1000.
Analyzing outliers: Robust methods to the rescue
Robust regression generates more reliable estimates by detecting and downweighting outliers.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.
Background reading
Altman, N. & Krzywinski, M. (2016) Points of significance: Analyzing outliers: Influential or nuisance. Nature Methods 13:281–282.
Two-level factorial experiments
To find which experimental factors have an effect, simultaneously examine the difference between the high and low levels of each.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.
Background reading
Krzywinski, M. & Altman, N. (2014) Points of significance: Designing comparative experiments.. Nature Methods 11:597–598.
Happy 2019 `\pi` Day—
Digits, internationally
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.
Check out art from previous years: 2013 `\pi` Day and 2014 `\pi` Day, 2015 `\pi` Day, 2016 `\pi` Day, 2017 `\pi` Day and 2018 `\pi` Day.