GeraldJarvis.com Because IT matters... sometimes ;-)

In this series of articles I will go over how to create dynamic charts in Excel that will keep showing the data for a rolling time period, say 13 months, without the need to be updated every time another month is added. This method can be applied for any other time sequence you choose, such as Years, Months, Weeks, Days, Hours, Minutes, Seconds or whatever scale you can think of. I will be using Months.
I am assuming you are familiar with Excel basics and know how to create named ranges. If you don't, there are plenty of articles and books on the subject and you should have these skills before attempting to create dynamic charts.