1 Reply Latest reply on Jan 20, 2019 10:38 PM by Mahfooj Khan

    Blended data quick table calculation error

    john.garrigan.1

      Hi,

       

      I have two data sources which I have blended on date, specifically quarter and year ("quarter year")

       

      My other data source contains information on Member Months and looks as follows:

       

       

      I wish to calculate the number of PA Requests per Member Month and calculate the percentage increase between 2018 Q3 & Q4. The formula for this metric is (PA Requests/Member Months)*12000

       

      I have created a calculated field with the following formula:

       

      SUM([Pa Requests])/SUM([MEMBER MONTHS].[Member Months])*12000

       

      When I drop this measure to the view I get the following figures which are correct, take the first row for Q3: (120621/38933431)*12000 = 37.17 and similarly for Q4 (127953/39410204)*12000 = 38.96 which is what is shown below.

       

       

      I now wish to calculate the % increase/decrease of these values between quarters.

       

      I then right click on the green pill (AGG(PA Requests per MM)) and use the quick table feature to calculate percent difference. When I do this I get the following figures:

       

       

      As you can see these figures are incorrect, (38.96-37.17/37.17)*100 = 4.8%

       

      I believe Tableau is using the underlying PA request figures from the very first screenshot to calculate the percentage increase: (127953-120621/120621)*100 = 6.078%

       

      Is there a way to get my figure of 4.8% rather than 6.08%?

        • 1. Re: Blended data quick table calculation error
          Mahfooj Khan

          Hi,

           

          I've tried to create mock up data using your screenshot and blend it found the expected output. See this

          Only difference is I don't have any filter in this view though you've Date field in filters shelf. Put your filter on context and check if this fix your issue else you can use join instead of blending. If you can provide some sample mock up of your data sources in excel then we can help you to resolve the issue.

           

          Mahfooj