Active verus inactive customers

The following example identifies the customers who purchased last year but haven't yet purchased this year.  

1. Create a measure for missing or inactive customers
   
   • Use DAX variables and time intelligence functions to produce two filtered sets of customer keys.

Count of Last Year Customers ex Current Year = 
 VAR Today = TODAY() VAR CurrentYear = YEAR(Today) VAR LastYear = YEAR(Today) - 1
 VAR LYCustomers = 
  SUMMARIZE(CALCULATETABLE('Internet Sales',
  FILTER(ALL('Date'),'Date'[Calendar Year] = LastYear)),Customer[Customer Alternate Key])
 VAR CYCustomers = 
  SUMMARIZE(CALCULATETABLE('Internet Sales',
  FILTER(ALL('Date'),'Date'[Calendar Year] = CurrentYear)),Customer[Customer Alternate Key])
RETURN
CALCULATE(DISTINCTCOUNT(Customer[Customer Alternate Key]),EXCEPT(LYCustomers,CYCustomers)) 

• Pass the time variables to the CALCULATETABLE() function and then group the keys by SUMMARIZE()

1. Visualize the measure in Power BI Desktop

• A visual level filter applied to the new measure exposes the specific 287 customers without a 2017 purchase yet