WEEKNUM in date table, SAMEPERIODLASTYEAR giving the wrong answer (off by by a few)

[Anonymous]

I am trying to find the net difference between previous years data based on a period using a slicer.  The slicer uses the WEEKNUM column from my Calendar table.  I have a measure that gives me a rate from my Data table. I created another measure to give me the rate for the previous year using:

PrevRate = CALCULATE([CurRate], SAMEPERIODLASTYEAR('calendar'[Date])

In the visual I am getting weird results

Weeks 1 to 39:

Year	CurRate	PrevRate
2017	312.16
2018	295.82	314
2019		298

Weeks  5 to 36:

Year	CurRate	PrevRate
2017	293.99
2018	274.58	294
2019		282

It's weird because the rates are sometimes very similar, but can be off by a lot as well. When I change the slicer to use the Month column the results match exactly.

[v-yuta-msft]

Hi jgoddard,

Are the date continuous? You may try PREVIOUSYEAR instead if the date value is not continuous. If this issue persists, please share some sample data or share some screenshot of your raw data and do mask the sensitive data.

Regards,

Jimmy Tao

[Anonymous]

The dates are continuous, however not necessarily YTD.  Some times we need to compare from Week 21, and sometimes from Week 16 to current.

[Anonymous]

It also does not sum properly when using the Date column (range is changed daily).

[v-yuta-msft]

Hi jgoddard,

Could you please share some sample data?

Regards,

Jimmy Tao