Track price changes on product in time

[Lamao]

Hello! 

I would like to compare average quantity sold 3 months before price change and 3 month after price change. Does anybody have idea of DAX to be used? I tried to use earlier but without success. Any advice much appreciated! Thank you...

Product	DatePeriod	Price	Quantity	Calculated column to identify change?
Product A	2018-01	100	5
Product A	2018-02	100	6
Product A	2018-03	120	2	X
Product A	2018-04	120	3
Product A	2018-05	120	1
Product A	2018-06	120	4
Product A	2018-07	120	2
Product B	2018-01	100	8
Product B	2018-02	100	7
Product B	2018-03	120	3	X
Product B	2018-04	120	2
Product B	2018-05	100	7	X
Product B	2018-06	100	8
Product B	2018-07	100	9

[Greg_Deckler]

See if my Time Intelligence the Hard Way provides a different way of accomplishing what you are going for.

https://community.powerbi.com/t5/Quick-Measures-Gallery/Time-Intelligence-quot-The-Hard-Way-quot-TIT...