previous weeks chart

[draacor]

I have a chart that shows data for a date range for a given week. How or what formula do i use to do another chart or a modification of the existing chart to also show the previous weeks data as well?

 

[draacor]

to be more specific, i currently have this formula for coming up with a count of the types of calls.

if {tickets.type} = 'I' and {tickets.open_date} >={?01StartDate} and {tickets.open_date} < ({?02EndDate}+1)
then 1
else 0

But it is only for the date range i put in. I need a way to take this same formula and do it for the previous week to see a comparison.