week over week measures giving two very different results

[Anonymous]

Hello Community  -  I am trying to diagnose why the results of these two different 'week over week' formulas are so different.  

In the first measure (which I know is correct) I am using a fully qualified column reference.    In the second formula, I am using a sumx measure.    You can see in my table that a change from 38 units returned in Week 33  to  52 units returned in Week 34, is indeed  a 36.84% change.  

Just trying to figure out what is wrong with that 2nd formula as I'd like to make use of the VAR functions.  

Week over Week Qty Change =

VAR lastWeekAmount =

CALCULATE (

SUM ( Merge1[Qty To Return] ),

FILTER (

ALL ( 'Date Table' ),

'Date Table'[Week Number]

= MIN ( 'Date Table'[Week Number] ) - 1

)

)

RETURN

DIVIDE ( SUM ( Merge1[Qty To Return] ) - lastWeekAmount, lastWeekAmount, 0 )

-----

Week over Week2 =

VAR CurrentWeek = SELECTEDVALUE('Date Table'[Week Number])

VAR CurrentYear = SELECTEDVALUE('Date Table'[Year])

VAR MaxWeekNumber = CALCULATE(MAX('Date Table'[Week Number]), ALL('Date Table'))

RETURN

SUMX(FILTER(ALL('Date Table'),

IF(CurrentWeek = 1,'Date Table'[Week Number]=MaxWeekNumber && 'Date Table'[Year]=CurrentYear - 1,'Date Table'[Week Number]=CurrentWeek - 1 && 'Date Table'[Year]=CurrentYear)),[SumX Qty to Return])

[v-lionel-msft · Accepted solution]

Hi @Anonymous ,

I have modified your second formula . Please refer to my .pbix file.

Best regards,
Lionel Chen

If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.

[amitchandak]

@Anonymous , when are not using year, it can week across year?

please use Rank approach suggested in my blogs

https://medium.com/@amitchandak.1978/power-bi-wtd-questions-time-intelligence-4-5-98c30fab69d3
https://community.powerbi.com/t5/Community-Blog/Week-Is-Not-So-Weak-WTD-Last-WTD-and-This-Week-vs-Last-Week/ba-p/1051123

[Anonymous]

@amitchandak    Hi Amit  -  I am not totally clear on your question.  

But if I do not have a year filter....so instead use a relative date  (past 30 days for example), I still get the same issue.   One formula works and one does not.  

[amitchandak]

@Anonymous , in the first formula you are using week number only. Same week number can be there across the year.  So I doubt that answer will match with one formula use year.

Check if my Rank approach can help you.