How Many Bubbles are Too Many Bubbles?

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Bubble Chart Mistakes - Dont use too many bubbles in your graphsIn How Many Links are Too Many Links, O’Reilly radar shows us this unfortunate bubble chart. (click on the image to see a bigger version)

I say unfortunate for the lack of a better word without sounding harsh.

Just in case you are wondering what that chart is trying to tell (which is perfectly fine)

Nick Bilton, who constructed this chart, got curious and went to the top 98 websites in the world and found out how many links they have on their home page. Then he used charting tools like processing to create the bathing bubbles you are seeing aside.

The conclusion ?

Too many bubbles can drown you. And also, top web sites have lots and lots of links on their home pages.

But seriously, apart from looking really pretty, does this chart actually provide that conclusion?

I think Nick and the O’Reilly radar team could have much better with a simpler and fortunate chart selection.

A histogram of # of links on popular home pages

like the one below would have been very easy to read and get the point.

Histogram - Links on Popular Home Pages - a better alternative

I showed some dummy data in the histogram, but when you create 2 histograms, one for popular sites (ranked below 5000) and one for not-so-popular sites (>5000) you can easily make the point and use the bubbles for a warm bath.

A better alternative is to show a scatter chart

with site rank on one axis and # of links on home page on another axis, that way a conclusion like Top Sites Links More can be easily established.

Scatter Graph - Showing that Top Sites Link More

Even a bar chart with number of links on each home page

could have been better than umpteen bubbles
Ordered Bar Graph Showing Number of Links on Home Pages
You could easily add a bar with “avg. number of links on non-popular sites” to contrast the linking behaviour of large sites wrt small sites.

But alas, we are treated to an unfortunate bubble chart that does nothing but look pretty (and ridiculously large)

What do you think ? How many bubbles are too many ?

Recommended Reading on Bubble Charts: Travel Site Search Patterns in Bubbles, Good Bubble Chart about the Bust. Olympic Medals per Country

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18 Responses to “Best Charts to Compare Actual Values with Targets – What is your take?”

  1. Andy Cotgreave says:

    Great post. I can't vote, though, because the answer I want to put down is "it depends". As with all visualisations, you've got to take into account your audience, your purpose, technical skills, where it will be viewed, etc.

  2. Jon Peltier says:

    I'm with Andy: It depends. Some I would use, some I might use, some I won't touch with a barge pole.
     
    Naturally I have comments 🙂
     
    The dial gauge, though familiar, is less easy to read than a linear type of chart (thermometer or bullet). It's really no better than the traffic lights, because all it can really tell you is which category the point falls in: red, yellow, or green.
     
    By the same token, pie charts are so familiar, people don't know they can't read them. Remember how long it takes kids to learn to read an analog clock?
     
    Bullet charts don't show trends.
     
    With any of the charts that have a filled component and a marker or ine component, it makes more sense to use the filled component (area/ column) for target, and the lines or markers for actual.

  3. [...] Best Charts to Compare Actual values with Targets (or Budgets … [...]

  4. Tony Rose says:

    I voted for #6 even though I agree with the other comments that it depends.

    The majority of the votes are for the #2, thermometer chart. I still have yet to understand what happens when you are above plan/goal, which was brought up in yesterday's post.

    Also, I agree with Jon in that it would be better to flip the series and make the filled part the target or goal and the line or marker the actual.

    I am also a fan of using text when appropriate if the data is among other metrics in a type of dashboard. Calling it out by saying actual and % achievement is a good option.

  5. Another "it depends" vote. Are you just looking at one or are you comparing a number of targets with actuals? You didn't include a text box. The problem with sentences is that they can get lost in a page of gray text. A text box can call attention to the numbers and line them up effectively.

    I'm with Jon: "Some I would use, some I might use, some I won’t touch with a barge pole" and I'm surprised that some of your readers voted for the last group.

  6. Bob Gannon says:

    Jon says:
    With any of the charts that have a filled component and a marker or line component, it makes more sense to use the filled component (area/ column) for target, and the lines or markers for actual.
    Why does this make more sense? I like 6 the way it is, although I would use a heavy dash for the plan/target marker.

  7. "It depends" is also my take. What I usually try to drill into my clients dashboard design is the fu ndamental difference between spot results (am I on target for this month) and long term trends.. I always try to create 3 different set of graphs to represent real perormance:
    - spot results vs objectives
    - cumulative results vs objectives
    - long-term trend (moving average) mostly) to see where we're going

  8. [...] Best Charts to Compare Actual Values with Targets – What is your take? (tags: excel charts) [...]

  9. Jamie Regan says:

    Jon says:
    With any of the charts that have a filled component and a marker or line component, it makes more sense to use the filled component (area/ column) for target, and the lines or markers for actual.
    Why does this make more sense? I like 6 the way it is, although I would use a heavy dash for the plan/target marker.

    I totally agree, Bob. I would normally favour a line for the target and a column for the actual, you can see quite easily then which columns break through the line, then.

  10. [...] best charts to compare actual values with targets — den Status mal anders zeigen, z. B. als Tacho [...]

  11. zzz says:

    Thermometer charts: "Not appropriate when actual values exceed targets" - this is easily solved by making the "mercury" portion a different color from the border, then you can clearly see where the expected range ends and the actual values keep going.

  12. Godsbod says:

    People seem to knock gauges quite a bit in dashboarding, but trying to show comparison of realtime data between operating sites and targets for each site can easily be done with a bank of gauges that have the optimal operating points at 12 o'clock.

    The human eye is great at pattern stripping, and any deviation of a gauge from the expected 12 position will quickly register with an operator and attract his attention. Using a colour background, or meter edge, will also indicate the sensitivity of a particular site.

  13. […] work laptop I have a favorites folder just dedicated to Excel charts.  Its got things like “Best Charts to Compare Actuals vs Targets” and “Best charts to show progress“. I love me some charts […]

  14. Albert says:

    I am wondering how will the plotting work, for some of the targets which may have been achieved before time. E.g. for the month of Jul the target was 226 and the actual was 219. So the chart will show a deficit in meeting the target by 7 points but what if this 7 may have been completed earlier in month of June. So ideally it not a deficit.

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