Changing Aggregate Formula from Week to Month?

Changing Aggregate Formula from Week to Month?

HI Guys,

I came across the following code to bring back a weeks worth of data.

1. Display number of tickets received on last week
Countif(Ispreviousweek("Request"."Created Time") = 1)

2. Display number of tickets CLOSED on last week (tickets were received on last week as well)
Countif(Ispreviousweek("Request"."Created Time")=1 and Ispreviousweek("Request"."Completed Time")=1)

3. Display number of tickets received on last week, but not yet CLOSE
Countif(Ispreviousweek("Request"."Created Time")=1 and"Request"."Request Pending Status"='Yes')

4. Display number of tickets CLOSED on last week and that ticket was received before last week
Countif(Ispreviousweek("Request"."Completed Time")=1 and Ispreviousweek("Request"."Created Time")=0 and Iscurrentweek("Request"."Created Time")=0)

How would I change this, so it reported on the previous month?  I did try and change previousweek to previousmonth.

Thank You