3 Replies Latest reply on Sep 25, 2018 6:06 AM by Jonathan Brough

    Linear extrapolation

    Roman Opeida

      Hi, guys! I have a cumulative line chart from the beginning of every month (columns - days, rows - running total of my X value). I need to extrapolate my chart to the end of the month with last X value in the data source (I have already got this value as single value in calculated field). How can do that?

        • 1. Re: Linear extrapolation
          Jonathan Brough

          Hi Roman,

          You could add the new calculated field to the trend calculation in a combined calculation and plot that. You would then want a way to determine what is the extrapolation, which can be done by another calculated Boolean flag (up to today, or after today) added to the Colour Card.

          Have you thought about dragging in the Forecast option (see under the Analytics tab, above the Data fields), instead of using your own calculated field ?

          Thanks,

          Jonathan

          • 2. Re: Linear extrapolation
            Roman Opeida

            Hi Jonathan,

            Forecast option is not available for me (grayed out), cause I use table calculations (running total) and I need to use value for the last day rather than forecasting.

            Would you be so kind to tell me a bit more about the way you suggest?

             

            The last number that I need to cumulatively sum for every day until the end of the month is 4722 (a calculated field called  "Last Day Number").

            How can I set values for the following days?

             

            Thanks,

            Roman

            • 3. Re: Linear extrapolation
              Jonathan Brough

              Hi Roman,

              Apologies, I misread and thought you already had a separate field for your post today forecast. What calculation are you planning on using for this forecast simulation ?

              Not sure how you would create it in Tableau directly without using either Data Prep or Alteryx. If you are drawing in from a database you could build some Custom SQL to simulate the historical records, adding to the date to roll it forwards.

              Thanks,

              Jonathan