Data Viz Done Right

April 17, 2013

Notes from the Visual Business Intelligence Workshop: Day 1 – Show Me the Numbers

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Stephen Few is running his three-day Visual Business Intelligence Workshop this week in Austin, TX.  He and I had been emailing back and forth and he thought maybe this wouldn’t be a worthwhile course for me, but I told him that I strongly believe that seeing someone teach in person is way better than reading books and sitting on webinars.  You simply can’t get the same level of interaction and communication without attending or conducting training live, in person.  I see this every time that I run training classes; those classes that are in person are way better.

Day one of the course, based on Stephen’s book Show Me the Numbers, has exceeded my expectations.  I’ve read all of Stephen’s books, so yes, much of the material was repeat, but the discussions in the class and hearing Stephen explain, in detail, his beliefs, extended the content way beyond what the book could possibly cover. 

Here are some of the key reinforcements and takeaways I noted from Tuesday’s class.  Many of these are “duh, of course” type of notes, yet good to always be reinforced.  This is a brain dump, so don’t expect any semblance of fluidity in my notes.

  • You should strive to include context and comparisons in every table of chart you create.
  • Line charts do NOT have to start at zero because you’re looking at patterns, unlike bars, which must start at zero because you’re comparing lengths. 

This was a big question I had before the course.  I typically always create line charts that include zero, but now I understand better why that’s not always necessary.  In the end, the patterns of the lines are easier to see when you do not start at zero.  Be careful though, you may have to alert your audience that the axis does not start at zero if they’re unfamiliar with the data.

  • There are eight types of relationship graphs:
    1. Time series
    2. Ranking
    3. Part-to-whole or contribution
    4. Deviation
    5. Distribution
    6. Correlation
    7. Geospatial (note this is different than geographical)
    8. Nominal comparison
  • “Don’t bury the truth under a layer of beauty or abstraction.”
  • There are four primary methods for encoding values:
    1. Points
    2. Lines
    3. Bars
    4. Boxes (which represent ranges of low values to high values)
  • ColorBrewer.org is a great resource for understanding color choices.
  • Adding data points to line charts is good for making comparisons between lines, but keep them light & small.  Don’t use separate shapes if you’ve colored the lines.
  • Bubble size is appropriate to use for data points if precise comparisons are not required.
  • Avoid dual-encoding.  I’m glad I asked about this, because it’s a practice I employ, but no longer will. 

As an example, if you’re looking at a map that has a circle for each state that is sized by sales, you should not also color the circle by sales.  If you want to use color, it should be another element that adds to the interpretation (like profit ratio).

  • This one shocked me – It’s ok to use pie charts on maps (assuming there aren’t but two or three slices) because there’s no better way to subdivide bubbles on a map.  In other words, pie charts are your only choice in this case.
  • Three good examples of representing a single distribution are histograms, frequency polygons and strip plots.  I’ve never used the latter two, so I’m going to be looking into those more.
  • Colors:
    1. Use only soft, natural colors.  Tableau’s medium palette works well.
    2. Use fully saturated colors for emphasis, otherwise they become visually exhausting.

Of course there was way more content than this; these were merely the key points that I wanted to ensure I reinforced to myself.  Look for summaries of the next two course as the week progresses.

1 comment :

  1. Andy,

    Great summary! Thanks for posting.

    Regarding your comments on pie charts on maps, I am very glad to know it is OK.

    I struggled with a better way to represent this viz in my latest case study (New product Introductions), but could not find a better way. This is the link: http://goo.gl/CNIuH

    It does not follow the 2 or 3 slices rule, but in most cases 2 or 3 slices are predominant.

    If you or someone else has a suggestion on how to better visualize this, please share!

    ReplyDelete