2 Replies Latest reply on Jun 30, 2016 12:05 PM by swaroop.gantela

    Linear Trend Line: Utilizing Indices

    Dennis Kwon

      Hello All, I'm plotting a linear trend line on a time series plot and I'm getting an linear equation that doesn't make sense because of the y-intercept value. I would much rather use the indices of the time stamps, however, I haven't been successful in obtain a linear fit using INDEX(). Any suggestions/guidance would be helpful.

        • 1. Re: Linear Trend Line: Utilizing Indices
          Dennis Kwon

          I figured that since no one has responded and I'm still relatively new with Tableau, I've attached a simple workbook to make the problem more clear .

           

          In the workbook you'll see the 2 linear trend lines:

          Trend line Equation 1:

          Avg. Value = 1440*Date and Time + -6.12252e+07

          Trend line Equation 2:

          Avg. Value = 10080*Date and Time + -4.28576e+08

           

          I want to use the indices rather than the serial value of the date/time. By doing that my y-intercept values should make more sense. Any suggestions/ leads on how to go about doing that?

          • 2. Re: Linear Trend Line: Utilizing Indices
            swaroop.gantela

            Dennis,

             

            I tried the plotting versus INDEX() and saw that it did change the slope,

            and now the y-intercept was 0 for Trend 1 and positive for Trend 2.

            Not sure if that is correct. Also saw that INDEX() shifted the graphs so that

            they no longer cross where they once did. Is the temporal crossing point important?

             

            209960trend.png