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Communicating with data visualization

Camille Seaberry, DataHaven

March 15, 2018

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Goal of this workshop

Data visualization is way too big a field to cover in one morning! But these are some starting places for improving your use of data visualization.

I'm not a data viz genius, so probably any of the charts I've made here could be improved upon.

Follow along: https://camille-s.github.io/viz

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What is data visualization?

The representation and presentation of data to facilitate understanding

-- Andy Kirk, "Data Visualisation: A Handbook for Data Driven Design"

Data graphics visually display measured quantities by means of the combined use of points, lines, a coordinate system, numbers, symbols, words, shading, and color

-- Edward Tufte, godfather of data visualization, "The Visual Display of Quantitative Information"

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Maybe you don't need a visualization

Chart serves some purpose, but you might be better off with just text:

  • Working men's median income is $51,367, compared to women's median income of $35,681
  • On average, working men out-earn working women by $15,686 each year
  • On average, women earn 69 cents on the male dollar
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Maybe you don't need a visualization

  • A few overview stats---especially if comparisons wouldn't be appropriate

from https://ct-data-haven.github.io/nhv2016/

  • Bullet points

from Community Progress Report 2016

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Questions to ask yourself

If you do need a visualization, be intentional about what you create

What's your purpose?

  • Comparing two or more observations
  • Comparing values changing over time
  • Showing parts of a whole
  • Finding relationships between values
  • Placing numbers on a map
  • Distributions of values
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Purpose

Comparing observations

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Purpose

Parts of a whole

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Questions to ask yourself

  • Who's your audience?
    • Make charts for yourself to understand your data as well
  • What's the purpose?
  • What do you need to communicate? What's the takeaway?
  • What can you do without?
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Focusing on your audience

Example: boxplots

Statisticians: 😍. General audience: 🤔

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Focusing on your audience

General audiences often more concerned with averages or summary figures, not distributions.

Or pair a simple chart with more detailed text like "Low-income rates vary greatly throughout Greater New Haven's census tracts, with rates in some tracts in the single digits, while many city tracts have rates over 50%."

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What's the purpose?

Hard to read, and unclear what the purpose is

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What's the purpose?

Purpose: show differences in income between towns

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What's the purpose?

Purpose: to show income by gender in each town

Alternatively, could order by largest pay gap

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Basic guidelines

  • Figure out what you're trying to show, and why
  • Use an appropriate chart/visualization type
  • Map ink to values
  • Get rid of junk and distractions
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Basic guidelines

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Basic guidelines

Previous guide: Curtis Newbold, The Visual Communication Guy

More detailed guide to picking charts: http://annkemery.com/wp-content/uploads/2017/10/AnnKEmery-FSI-Visualization-Handout.pdf

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Bad habits

  • Muddying your data
  • Telling inaccurate stories
  • Visual cues that are flashy but contribute nothing/interfere with understanding (see any cable news channel)
  • Unexamined use of pie chart, 3D, shadows, etc
  • Encoding information that isn't actually there---e.g. do you actually need all those colors?
  • Comparing things that are not actually comparable
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Bad habits

Data mud

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Bad habits

Fox News-ing your data

fox news

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Bad habits

3D

If you aren't solving differential equations or plotting terrain, you probably don't need 3 dimensions.

Where should you be reading values?

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Bad habits

Pie charts

Google "pie charts are evil." There's almost always a better way.

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Bad habits

Pie charts

Stacked bars are easier to compare between observations

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Bad habits

Visualizing information that isn't actually there

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Few notes on visual perception

Visual perception is a huge field of psychological study. A few basic ideas:

  • It might be hard to show minute differences---but it also might not be necessary
  • Ink to value---e.g. scale bubbles to area, not diameter
  • Colors convey meaning
    • Cultural significance, emotion, politics
    • Color scales might imply direction
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Few notes on visual perception

Can you spot difference between tract with 20% rate and 25% rate? Is it really necessary?

How would you compare poverty rates between non-adjacent parts of the region?

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Few notes on visual perception

Putting values into buckets makes it easier to spot patterns & differences---might sacrifice detail but gain clarity

Now how easy is it to compare different areas?

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Few notes on visual perception

What do these colors signify?

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Few notes on visual perception

Do these colors tell the story of change more accurately? What meaning do we give to these colors?

Red = positive values, but negative outcome (e.g. increase in low-income rate)

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Activities!

Find what doesn't work

In groups, visit WTF Viz viz.wtf. Find your group's favorite example of what not to do, and discuss:

  • What went wrong?
  • What is the visualization's purpose? Or is the purpose not even clear?
  • How could you achieve this purpose differently?
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Activities!

Improve a visualization

Use the Data Visualization checklist to rate either a chart you or a colleague has made recently, or the chart on the next slide

Checklist: bit.ly/vizcheck

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Improve this visualization

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Some improvements

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Resources

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Tools

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Stuff I've made

DataHaven B-sides blog: ct-data-haven.github.io

The code that generated these slides is on GitHub: https://camille-s.github.io/viz

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Goal of this workshop

Data visualization is way too big a field to cover in one morning! But these are some starting places for improving your use of data visualization.

I'm not a data viz genius, so probably any of the charts I've made here could be improved upon.

Follow along: https://camille-s.github.io/viz

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