Feb 162012
 

Many companies use 4-4-5 calendar which ends up with an extra week approximately every 5 years.  This makes comparing periods challenging when you encounter the 53 week year.  This is especially challenging when reports are driven from an SSAS cube data source, and you want to build in the logic to automatically compare the correct This Year period with the corresponding Last Year period as per the companies business rules.  There is a way to do this.  It isn’t pretty, but it works.  The reporting will automatically choose the correct matching period in the context of a 52 or 53 week year.

There are some possibilities.  A company may want to compare the year after a 53 week year by shifting each week of the 53 week year by 1 week.  For example, if 2012 is the 53 week year then we want to compare:

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Another possibility is that the company may want to compare the 53 week year by shifting the previous year weeks, or in some other way identify whether a week belongs to a 52 or a 53 week year for purposes of comparing periods.  This requires a bit more under the hood, but also doable. 

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COMPARE THE YEAR AFTER A 53 WEEK YEAR WITH THE CORRESPONDING SHIFTED WEEKS FOR LAST YEAR

This is relatively easy.  Basically you make all your Last Year (LY) calculations and LY Period To Date calculations by counting back 52 weeks from the current week.  The week in your hierarchy must always be selected in your query.  I use Fiscal Week ID as the level to which I map all previous period calculations, so the Fiscal Week ID must be selected in all queries using these calculations.

This calculation will return the [Sls Dollars LY TW] (last year this week)

(PARALLELPERIOD
    ( [TIME].[Week Period To Date].[Fiscal Week ID], 52, [TIME].[Week Period To Date].CURRENTMEMBER  )
,[Measures].[Sales Dollars])

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Notice how 2013 Wk 1 shows 2012 Wk 2 for the Sls Dollars LY TW.  And 2012 Wk 2 shows 2011 Wk 2 as desired.

For Periods To Date you can do this the same way.  You would like the LY QTD for 2013 Wk1 to show the QTD up to 2012 Wk 2.

This query returns [Sls Dollars LY QTD].

Aggregate
(
  PeriodsToDate
  (
            [TIME].[Week Period To Date].[Fiscal Quarter],

             PARALLELPERIOD
            ( [TIME].[Week Period To Date].[Fiscal Week ID],52,
                [TIME].[Week Period To Date].CURRENTMEMBER
            )
  ),
[Measures].[Sales Dollars]
)

Here are the results.  Again, you must have the Fiscal Week Id from the hierarchy selected in your query for this to work.

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Notice how 2013 Wk 1 shows 2012 Wk 2 QTD for the Sls Dollars LY QTD. And 2012 Wk 2 shows 2011 Wk 2 QTD as desired.

IDENTIFY WHETHER A WEEK FALLS IN A 52 OR A 53 WEEK YEAR FOR USE IN CALCULATIONS

Here is an example of how to identify whether a week falls in a 52 or 53 week year, in order to be able to use in your calculations.  It isn’t pretty, but it does the job.

1.  Add a column to your DIM_Date table to identify whether a year has 52 or 53 weeks. 

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2. Add a named calculation to the DIM_Date table in your cube Data Source View. 

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The calculation is FiscalWeeksCount*10000+FiscalYearID. This will give you an integer which begins with either 52 or 53 and ends with the Year.  For example 522011 or 532012.

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3. Add this calculated field to your Time dimension. Add it as a level of your Time Hierarchy, directly after Fiscal Year.  You may prefer to create a new hierarchy specifically for reporting needs so as not to confuse users. 

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The reason the Year is appended to the Fiscal Weeks Count, rather than having the Fiscal Year roll directly up to Fiscal Weeks Count is that that would disturb the order of the children. 53 would come after 52 in the hierarchy, and therefor 2012 would come after 2013. The MDX calculations use relative position in the hierarchy to find a previous period, so the weeks must remain in the correct order in the hierarchy in order for this to work.

4. Save the change and rebuild the cube. Now you can reference this level in the hierarchy in order to identify how many weeks in the fiscal year.  You can use it in a case statement, like this:

CASE
WHEN [TIME].[Fiscal Weeks Count Year].CURRENTMEMBER.MEMBERVALUE > 530000 THEN
(PARALLELPERIOD ( [TIME].[Week Period To Date].[Fiscal Week ID], 53, [TIME].[Week Period To Date].CURRENTMEMBER ), [Measures].[Sales Dollars] )
ELSE
(PARALLELPERIOD ( [TIME].[Week Period To Date].[Fiscal Week ID], 52, [TIME].[Week Period To Date].CURRENTMEMBER ), [Measures].[Sales Dollars])
END

This determines if the current selected week falls in a 52 or a 53 week year, and calculated the corresponding previous period accordingly.  You could use ANCESTOR if you want to find out if the previous year was a 52 or a 53 week year.  You now know where your selected week is relative to a 53 week year and can use this information as needed.

May 282011
 

Not to beat a dead horse, but this is another SSRS aggregation situation against a cube data source that can be solved by math.  This is the third in a series, and I suspect there will be a few more, since each situation is different. 

You can get the concept from my previous posts Filter Zeros from a Percent Increase and Aggregating Last Child values.  This one is even more complicated, but I’ll give the quick and dirty version.

The client wants a report that allows the user to choose a week, and have report columns for the most recent day in that week (so it will be Saturday for all past weeks, and today for the current week), for the week-to-date, and for the full week.  This get tricky because some of the values in these sets of columns include most recent day Last Year, and week-to-date Last Year.  I can’t filter the data set because some of the columns need the full week values for Budget and for Last Year, even if we’re only part way through the week.  Below is a report with the weekdays toggled open so you can see exactly how the values are summing up for the groups.  Thursday is the most recent day in the week, so it is the only one included in the Thursday totals.  Sunday to Thursday are included in the Week-To-Date totals. 

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To accomplish this I use math to zero out any unwanted values.  The math itself takes some thinking, and every situation is different. I put the values in a spreadsheet and play with them until I get the right combination.  Here is how I solved this one.

CREATE TWO FACTORS – Week-To-Date and Most Recent Day

The end goal is to create two multipliers, one for Most Recent Day, and one for Week To Date.  You will be able to use these multipliers on any measure in your data set to filter out unwanted values.  

The user can select a single week for the report.  The report dataset must contain the integer value of the Week Number out of the parameter select by the user.  **Note: this solution only works if the weeks in your cube are numbered uniquely and consecutively over time.  So the first week in your Date table should be week one (or whatever starting point you choose), and each week number thereafter should be greater than the last.

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1. CREATE NEW FIELDS IN THE REPORT DATASET PROPERTIES

Double click on your dataset and go to the Fields tab in the Dataset Properties.  Click on the Add button and select Calculated Field.

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2. FIRST WE FIND THE MAXIMUM DAY FOR THE SELECTED WEEK

Add the following Calculated Fields. The end goal is to create two multipliers, one for Most Recent Day, and one for Week To Date.  You will be able to use these multipliers on any measure in your data set to filter out unwanted values.  See Excel screenshot below for examples broken down for current week and previous week.

1. NowDay  – This gives me the day number of today from 1 to 7

=DatePart("w",Now(),FirstDayOfWeek.Sunday)

2. CurrentWk  – There is a hidden parameter  in the report defaulting to whatever the week number is of today.  Example today could fall in week # 319 according to my DIM_Time table. **

=Replace(Mid(Parameters!CurrentWeekID.Value,InStr(Parameters!CurrentWeekID.Value,"].&[")+4,10),"]","")

3. Floor  – The floor returns either a 1 or a 0.  It returns a 1 if the week selected is the current week, otherwise it returns 0. 

=FLOOR ( Fields!Fiscal_Week_ID.Value/Fields!CurrentWk.Value )

4. Ceiling – The ceiling returns either a 7 or a 0.  It returns a 0 if the week selected is the current week, otherwise it returns a 7.  I use a +1 to prevent a divide by zero.

=(CEILING( (Fields!CurrentWk.Value-Fields!Fiscal_Week_ID.Value) / (ABS(Fields!CurrentWk.Value-Fields!Fiscal_Week_ID.Value)+1) ))*7

5. MaxDayTW –This is the maximum day number (1 to 7) for the week selected.  If it is the current week it will be whatever number day of the week today is.  If is a past week it will return a 7.  So if today is Wednesday, and my week starts on Sunday, then MaxDayTW will be 4. The way it works is if the current week is selected then the Ceiling will be zero, and we will keep the  NowDay value.  If it is a past week, then the NowDay value will be zero’d out and the Ceiling will be 7, making it the MaxDayTW = 7, the last day of the week.

=(Fields!NowDay.Value*Fields!Floor.Value) + Fields!Ceiling.Value

6. MaxDayTW_Name – This gives the weekday name for the MaxDayTW that we calculated – Monday, Tuesday, etc. to be used in the column header of the report.

=WeekdayName(Fields!MaxDayTW.Value)

3. THEN WE CREATE THE MULTIPLIERS

Add the following calculated fields:

7. WeekToDate_multiplier – This will return a 1 or a 0.  It will be a 1 for all days which are less than or equal to the MaxDayTW, and zero out any unwanted days in the week-to-date.

=CEILING  (  FLOOR ( Fields!MaxDayTW.Value / Fields!Day_Of_Week_ID.Value ) / ( Fields!MaxDayTW.Value / Fields!Day_Of_Week_ID.Value )  )

8. MostRecentDay_multiplier – This will return a 1 or a 0.  It will be 1 for the most recent day of the week and a 0 for any other days of the week.

=FLOOR (Fields!Day_Of_Week_ID.Value /Fields!MaxDayTW.Value)*Fields!WeekToDate_multiplier.Value

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4. USE THE MULTIPLIERS IN YOUR REPORT

You can either create additional calculated fields in your dataset, or you can just apply the multipliers directly in your report.  I prefer to use them in the report so I don’t have to track back to multiple places to find out exactly how a calculation is working.  Be sure to use the multiplier BEFORE aggregating, since you want to multiply the individual rows, not the aggregate.

Examples:

1. To get Most Recent Day Sales $ use this calculation:

=Sum(Fields!Sales_Dollars.Value*Fields!MostRecentDay_multiplier.Value

2. To get Week To Date Sales $ for Last Year use this calculation:

=Sum(Fields!Sls_Dollars_LY.Value*Fields!WeekToDate_multiplier.Value)

Here are the results. The weekdays are toggled open so you can see exactly how the values are summing up for the groups.  Thursday is the most recent day in the week, so it is the only one included in the Thursday totals.  Sunday to Thursday are included in the Week-To-Date totals.

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This is not a simple solution, but once it is in place it is very simple to use.  It gets around all the complexities of having to use Custom Code to sum up each different measure for each different group in your report.  It also allows you to have repeating headers on each page rather than having to hold your table within a List to make the Custom Code work properly in all renderings.  Get the two multipliers right, and you can aggregate as many measures as you like without any hassle at all.

** It’s worth repeating that this solution only works if the weeks in your cube are numbered uniquely and consecutively over time.  So the first week in your Date table should be week one (or whatever starting point you choose), and each week number thereafter should be greater than the last.

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