Date Hierachy & Measures

[Sotirios]

I am building a dashboard for a digitisation project, and one of the requirements is to be able to see how many Images are produced over a variety of time periods- days, months, quarters for example.

The DB I have connected to records the cumulative number of images for each workflow stage in a column called 'ImageCaptures' for each day. Therefore I set up the following Measure to work out the difference between Cumulative total for a day (ReportDates), and it's corresponding value the day before. Here is the DAX formula:

ImagesDailyTotal = (SUM(SharepointRecordsComplete[ImageCaptures])) - (CALCULATE(SUM(SharepointRecordsComplete[ImageCaptures]),PREVIOUSDAY(SharepointRecordsComplete[ReportDates.Date])))

However, I have noticed some unusual behaviour for the visuals I produce, whether I use the flat ReportDates.Date vs the Date Hierachy. The exported data below should show what I mean:

ReportDates.Date	ImagesDailyTotal
23/06/2015 00:00	110606
24/06/2015 00:00	774
25/06/2015 00:00	3231
26/06/2015 00:00	1461
27/06/2015 00:00	0
28/06/2015 00:00	0
29/06/2015 00:00	804
30/06/2015 00:00	2365
01/07/2015 00:00	644
02/07/2015 00:00	1954
03/07/2015 00:00	1591
04/07/2015 00:00	0
05/07/2015 00:00	0
06/07/2015 00:00	1203
07/07/2015 00:00	680

Year	Quarter	Month	Day	ImagesDailyTotal
2015	Qtr 2	June	23	110606
2015	Qtr 2	June	24	111380
2015	Qtr 2	June	25	114611
2015	Qtr 2	June	26	116072
2015	Qtr 2	June	27	116072
2015	Qtr 2	June	28	116072
2015	Qtr 2	June	29	116876
2015	Qtr 2	June	30	119241
2015	Qtr 3	July	1	119885
2015	Qtr 3	July	2	121839
2015	Qtr 3	July	3	123430
2015	Qtr 3	July	4	123430
2015	Qtr 3	July	5	123430
2015	Qtr 3	July	6	124633
2015	Qtr 3	July	7	125313

I would like to be able to use the date hierachy, espcially with the drill down functionality in the bar graphs. Have a fundamentally misunderstood how dates work in Power BI? How can I resolve this?

[DataInsights]

@Sotirios,

The approach I take when source data contains cumulative amounts is to create a calculated column for daily amounts. This makes the data easier to use, and will result in faster visuals since the daily amounts are calculated during dataset refresh. It's recommended to create a date table (mark it as a date table) with the various columns you need such as Year, Quarter, etc. Create a relationship between the date table and your main table, and then use fields from the date table in your visual.

ImagesDailyTotal = 
VAR vDate = SharepointRecordsComplete[ReportDates]
VAR vPreviousDate =
    CALCULATE (
        MAX ( SharepointRecordsComplete[ReportDates] ),
        ALL ( SharepointRecordsComplete ),
        SharepointRecordsComplete[ReportDates] < vDate
    )
VAR vPreviousAmount =
    CALCULATE (
        SUM ( SharepointRecordsComplete[ImageCaptures] ),
        ALL ( SharepointRecordsComplete ),
        SharepointRecordsComplete[ReportDates] = vPreviousDate
    )
VAR vResult = SharepointRecordsComplete[ImageCaptures] - vPreviousAmount
RETURN
    vResult