Use variance line items to show multiple time periods in a waterfall chart

A useful trick for showing line item data across more than 1 time period. As you can see from the module grid view, the first line item pulls in 2013 Sales, then the next 2 use the lag formula function to show variance between the 2013 and 2014 data for those line items. The Sales 2014 line needs to be a summary item i.e. a sum of the above line items, in order for the waterfall chart to work. This can then be repeated for multiple time periods, as above the final line item Sales 2015 needs to be a sum of the other line items.