Reader Poll: Should the axis for bar charts always start at zero?

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It all began with my Excel Dashboard Tutorial – Making a dashboard with player statistics. I have used bar charts with axis whose minimum is not zero, to create a dramatic effect in the charts. See below:

excel-barchart-rule-breaking

Jon Peltier commented saying that,

Rule #1: Bar and column chart value axes should start at zero. Since the lengths of bars and columns represent their values, starting at a position other than zero will lead to a misleading display.

As always Jon raised an excellent point. I liked it so much that I wanted to get your opinions on this axis scaling issue.

What do I think about this visualization rule ?

First the positive points about the rule:

  • If you start axis at non-zero values, it gives a wrong impression about the data. In my example above you might end up thinking the top value is actually 10 times that of bottom value.
  • The rule helps easy interpretation of data, since everything starts at zero.


Now the negative points about the rule:

  • Not all data starts at zero (like the above with values ranging from 8000 to 12000). So when you create a bar chart for the data (why only bar charts, because they are easy to make and read) often you end up creating charts from which making out any analysis could be slightly difficult
  • Breaking this rule helps in creating dramatic effect on your charts, one of the reasons we use them. Often when you use data with narrow range, creating dramatic effect could be difficult. Axis adjustments can help (you may want to try logarithmic axis scale as well)

Finally, I think this rule can be broken as long as we have right data and make alternative arrangements (like adding data labels) to ensure correct interpretation. Since this is a standard people have come to expect, it is better to make it clear to your audience about the axis range.

What do you think about the charting rule: Bar and column chart value axes should start at zero.

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7 Responses to “Project Dashboard + Tweetboard = pure awesomeness!!!”

  1. Dan Murray says:

    I would like to see actual hash-tagged DM tweets go out to the specific information consumers. That would be an interesting way to communicate the key daily data to interested parties.

    A Twitter-like secure application like Yammer might be a good fit with this.

    For example, how about daily tweets to selected user groups (secure) that would display sales, bookings, cash receipts, cash disbursed and a second version that would show the same info for MTD, QTD or YTD figures.

  2. Aires says:

    @Dan, it would be great. I did not taught about implementing it on this dashboard because twitter is blocked to the whole intranet here. However, there's a discussion here about how can we send these tweets to blackberries (probably through e-mail) automatically. (I'd like to see this implemented on a jabber restricted network as well, but here it'll probably not happen)

    The wrap-up versions you mentioned doesn't apply to my particular scenario, but on a sales tweetboard it would be a great tool indeed - choosing who will receive which message according to hashtags. I'll think on something, thanks for the advice. 🙂

    (Ah, btw, I'm Fernando... 🙂 )

  3. Chandoo says:

    @Dan: That is a fun idea. Instead of tightly integrating twitter functionality with a dashboard, i think it would be cool if we have a "tweet this" button that users can click after selecting a range of cells. We can easily show a dialog with the concatenated output of the selected cells and ask user to edit the text and eventually "send to twitter".

    For eg. you can select the annual sales figure cell and click on "tweet this" button upon which a dialog will show the value. Then you can pre-pend it something like "DM @boss look at our sales this year: "

    @Aires.. thanks once again.

  4. Wow it looks really good. Not sure though how much the tweet facility would help in real world project management, but certainly having a dashboard on a project should be a key deliverable when learning how to manage a project

    The other use of this is during the software development life cycle especially when you have parallel streams of development and testing going on. Using a dashboard is a quick way for everyone on the team to see where the project is at and how it all fits together.

    Regards

    Susan de Sousa
    Site Editor http://www.my-project-management-expert.com

  5. Sue says:

    Hi Chandoo,
    I purchased the project management toolkit but the dashboard shown above with the imbedded scroll bars. Is it included in the project pack??
    Thanks

    Sue

  6. XLCalibre says:

    The gantt chart section of this dashboard is similar to one I have recently created: http://xlcalibre.com/hr-dashboard-gantt-chart-traffic-light-reportIt has a similar approach with scroll bars, but has a couple of additional features. I've tried to incorporate a traffic light report element, and also allow the timescale to adjusted so that can view it by days, weeks or months.I really like the other tables that you've incorporated, I may well try to replicate them to improve my version!

  7. I am a monitoring and evaluation consultant in international development, and one of the services I offer is to help non-profits and foundations develop performance dashboards.  I often advise them to develop dashboards for ongoing programs, rather than for one-time or pilot projects, because of the time involved.  I am trying to find out from a few people how long it takes you to develop a project management dashboard, and to what extent the indicators vary from one project to the next.

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