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

By: jerome cukier

jerome cukier — Tue, 18 Aug 2009 14:36:14 +0000

I humbly disagree with Jon. I’ve been defending the opposite argument in heated debates with colleagues (I work in government statistics)

Graphs result from choices made by their author. As such, they are interpretations of data and cannot be neutral or objective. So all graphs could be called misleading.

My counter example would be dow jones statistics. If we represented them as starting from 0, what happened in the past 6 months would look like a ripple whereas it’s a once-in-a-lifetime change. Financial services usually represent this with a non-0 origin.

Just because you adjust your graph to make a point doesn’t make it wrong, especially if you have a story to back up your choice. However, if you use such a graph to push a false conclusion, then this is lying.

By: Pandurang Baliga

Pandurang Baliga — Wed, 31 Dec 2008 08:39:59 +0000

take a look at http://peltiertech.com/Excel/Charts/BrokenYAxis.html
it tells about breaking the axis into segments to get around the problem in discussion…
what are your thoughts on
1. the appropriateness of this way of data representation
2. any other better ways to do this…

By: Colf

Colf — Wed, 26 Nov 2008 09:54:35 +0000

No graph or design is good or bad in itself. Ask yourself what you would like to achieve.

For performance dashboards or anything that people will continuously look at to evaluate or compare performance, I believe, X-Axis scales not starting at 0 should never be used.

If you want to make a sales pitch, leave out and move X-Axis for exaggeration. best to be combined with a ppt, where you flip to the next slide after 10 seconds (if you leave out X-axis scale like in the example you make it worse).

Apart from this, and depending on the purpose again – I would not advise to put values into a bar. A scale works better for pleasing design, as the last 2-3 digits are mostly distracting.

@Robert/Bruno
I like the idea of making this a button. Macros would do the trick, adding a button to switch to lowest value/move to 0. Highlighting the selection above the graph.

By: Best of Pointy Haired Dilbert - Oct 2008 | Pointy Haired Dilbert - Chandoo.org

Mon, 03 Nov 2008 09:02:52 +0000

[...] Reader Poll: Should the axis for bar charts always start at zero? [21 October] [...]

By: Chandoo

Chandoo — Mon, 27 Oct 2008 14:02:37 +0000

@Derek: agree, log scales are more suitable for line charts or xy plots. I have rarely seen bar charts with log scales.

@Bruno.. you are welcome

By: Bruno@Brazil

Bruno@Brazil — Mon, 27 Oct 2008 03:45:14 +0000

Thank you Robert and Chandoo, you not only answered my question, but told me how to be able to change the graphic in two different ways. Robert’s idea seems to be more direct, while Chandoo’s one seems to be more easily to handle and to pass it on to others. Once again, thank you guys.

By: derek

derek — Fri, 24 Oct 2008 13:53:40 +0000

Log scales are fine, but, again, *not for bars*. For one thing, log scales have no zero: it’s infinitely far off to the left.

The thing about bars is that you’re reading the length of the bar as a quantity, so it has to be visibly proportional in size to the quantity reported in the number. Anything that interferes with that means you can’t use bar lengths.

By: Sports Statistics Dashboard in Excel - Few More Alternatives | Pointy Haired Dilbert - Chandoo.org

Fri, 24 Oct 2008 13:28:32 +0000

[...] of all, thanks everyone for making the should you always start barcharts at zero? discussion lively. Almost everyone felt that we should start bar charts at [...]

By: Chandoo

Chandoo — Fri, 24 Oct 2008 12:36:39 +0000

@John … On “logarithmic” scale, actually it makes sense to use it when you have data with exponential trends (like distance between earth and nearest planets, star etc. or the US Debt in the last few decades…)

And it is fairly normal to use logarithmic scale since it is accepted in scientific community. But using it office for day to day purposes can be painful because not many people may remember the logarithm stuff from school and cant correlate it to the point.

What do you think?

By: John Nevill

John Nevill — Fri, 24 Oct 2008 01:07:34 +0000

In the past, I’ve used a scrollbar (linked through VBA) to allow zooming or scrolling. If the scale of your multiple series is way off and VBA isn’t your thing, a logarithmic axis may do the trick as well (right click on the axis, choose scale, and click “Logarithmic…”

That brings up a similar question though, is using a logarithmic scale deceiving/confusing for a user?