Prior Month Vales for a existing measure which aggregates from daily to monthly.

[Anonymous]

I have a table with daily observations.  I have an existing measure (Total_Visits_Sum) that provides the data on a monthly or quarterly basis based on the date I use for the axis.  If I use a custom column in the calendar for MMM-YY the data automatically gets aggregated.

Total_Visits_Sum = SUMX (

SUMMARIZE (

'Data',

'Data'[Date]),

CALCULATE (

SUM ( 'Data'[Visits])))

My question is how do I get the prior month's value to compare, so I could do a month-over-month change?  I have seen the examples that do this but only when the underlying frequency of the data is monthly, not aggregated like I am doing.  

[daxer-almighty]

@Anonymous 

Marco Russo on time-intelligence in Power BI: https://youtu.be/FxiAYGbCfAQ

Please watch this in order to not make mistakes that others do by thinking they can get away with not learning the basics and the theory behind DAX.