SubscribeUsing Combo Charts to Group Related Time Events [Charting Goodness]
This is a guest post by Paresh Shah
In his latest book, Now You See It
On pages 165 and 166 of the book, Few discusses how grouping related time intervals can facilitate analysis of data. As an illustration he explains that when viewing data of daily website visits, it helps in separating weekdays and weekends to differentiate expected traffic during these periods. The use of this technique would make it easier for the analyst to identify any anomalous movement in ether the weekend or the week day.
Fortunately excel combo charts can help you do that.
Given below is a combination chart of daily visits to a web site [ hypothetical ] where in the days of the week are shaded. The website visit data has been plotted as a line chart.
The website visit data has been plotted as a line chart. The shading has been achieved by using column chart – the data for the secondary series has been plotted on a second axis. A constant data value for Monday to Friday, 3 and a second constant value for Saturday and Sunday, 0 has been assigned for each date of the month. The secondary axis has thereafter been hidden. The maximum value for the second axis has been manually set at 3 to get the columns to run from the top to bottom and gap between the columns has been set to zero [ Format data series ->Gap width->No Gap ]. The secondary axis has thereafter been hidden.
The concept can be used for other groupings too, months grouped by year, by quarter etc without too much effort.
Download this excel combo chart and play with it to learn more
Click here to download the tutorial workbook and learn by changing things.
Added by PHD
Thank you Paresh. That is an innovative way to achieve zebra lines / bands on the charts to group related events.
Hello there, my dear reader, if you have enjoyed this charting trick, say thanks to Paresh.
Further Resources on Excel Combo Charts
- Excel combo charts – What are they and how to make one?
- Make a combination chart in Excel in 15 seconds [video tutorial]
- Using combination charts to make a timeline to show project milestones [project management using excel]
PS: the link to Now You See It
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At Pointy Haired Dilbert, I have one goal, "to make you awesome in excel and charting". PHD is started in 2007 and today has 300+ articles and tutorials on using excel, making better charts. 
Thanks for the article & attached spreadsheet Paresh.
Do you think the column plots on the secondary axis could also be used to more easily mark key weeks (eg. when a new product is released?
Thanks both, Paresh and Chandoo, for this article.
The first idea that crossed my mind after reading this, is to combine it with the waterfall chart I’ve created to show monthly data, and use this technique to group by quarters, to easily identify those periods.
Thanks !!
This is awesome. I love this blog. I have dealt with this issue before. Usually my issue is monthly anomolies caused by fiscal months of 4 weeks followed by 4 weeks, and then 5 weeks in each quarter. This causes a spike in March, June, Sept., and Dec. It’s one reason I prefer to look at quarterly trends rather than monthly. This chart is quite nice to see these effects. Is there a way to just toggle between two charts? One of weekends and one of weekdays?
I couldn’t see the shading, but when I downloaded, I was able to darken it a bit. THANKS for this.
Great community here ! Thank you too.
Geoff – We can do this if we put the constant value only for the days of the key week with zero for others. It would shade that week.
Art – We could create another series, with constant on the weekend days. Plot this on the secondary axis also. Hide one of the series [ no fill and no line] as required. This would achieve the effect.
Great community here ! Thank you too.
Geoff – We can do this if we put the constant value only for the days of the key week with zero for others. It would shade that week.
Art – We could create another series, with constant on the weekend days. Plot this on the secondary axis also. Hide one of the series [ no fill and no line] as required. This would achieve the desired effect.
@Art… I have taken your query and posted an extension to this tutorial where you can learn how to dynamically switch focus from say weekdays to weekends. Check it out http://chandoo.org/wp/2009/08/27/dynamic-event-grouping-in-charts/