2 Replies Latest reply on Sep 17, 2012 7:01 PM by Steve Haroz

    Standard error by category

    Steve Haroz

      My data has the following columns:

      • X - numerical dimension (integers 1-5)
      • Y - numerical measure
      • User - text dimension (Adam, Beth, Chris, Dan)


      There are multiple rows of data for each combination of X and User. Plotting a line of the average Y along X is simple enough.


      What I need to show is the average and standard error across individual user averages.

      1. Find the average Y for each X for each User. (avg for Adam, avg for Beth...)
      2. Find the standard error between these User-averages.
      3. Plot the average for each across users (the average of the averages) where the thickness (reference band?) is the avg +/- the std error.


      Could any one offer advice on how to accomplish this in Tableau?


      Edit: clarified 3.

        • 1. Re: Standard error by category
          Tracy Rodgers

          Hi Steve,


          When the measure is placed on the view, the aggregation can be changed. Right click on it and select Measure-->Average. Another instance of the measure can be placed on the view, and to find the Standard Deviation, right click and select Measure-->Ste. Dev.


          Then, a calculated field can be created to find the +/- on the std error.


          Hope this helps!



          • 2. Re: Standard error by category
            Steve Haroz

            Hi Tracy,


            Sorry I wasn't clear in the original message. The line I want to plot is the average of the averages.


            For each user, take the average. Then find the standard deviation and average of those averages.


            I understand how to create a calculated field, but I can't figure out what to put to make the average and standard deviation of the user averages.