4 Replies Latest reply on Aug 21, 2018 7:19 AM by meenu choudhary

    Understanding for LOD

    Raiyan k

      Hi Team,

       

      I would like to know is there anyway to understand LOD's in simple manner (Layman's words).

       

      Honestly speaking i tried out google and youtube videos, but unfortunately after doing practise also i am not able to understand the same.

       

      Awaiting for the reply from Viz experts.

       

      Regards,

      Raiyan.

        • 1. Re: Understanding for LOD
          Jim Dehner

          Ok

          LOD's are formulas that create a new level within the data set - a virtual level - that is at a higher level than the data itself -

          While LODs require you to aggregate data they are not aggregates in themselves and therefore can be further aggregated in calculations, other LOD's or table calculations.

           

          when processing an LOD Tableau will make combinations of all the dimensions that precede the colon(:) and then aggregate them based on what follows the colon so if you have an lod like  Demo= {fixed Category, Region, color :sum(sales) } and there are 3 categories, 4 regions and 2 colors - tableau now ill have a data level with 3x4x2 = 24 entries that are the sum of sales -

          you can then use those 24 entries like any  disaggregate   date eg dragging Demo to the viz with Avg(Demo) will take the average of the 24 data elements

          Demo will also be affected by filters - if you have a filter on color to use only 1 of the 2 colors then Demo will only use the 12 remaining data elements

           

          Suggest you take a basic example with 2 dimensions and go through fixed, include, and exclude and see what they as stand alone LODS then use them in the next level calculation

           

          Jim

          If this posts assists in resolving the question, please mark it helpful or as the 'correct answer' if it resolves the question. This will help other users find the same answer/resolution.  Thank you.

          • 2. Re: Understanding for LOD
            sudheer.kumar.5

            Hello Raiyan,

             

            Check the below whitepaper:

             

            https://www.tableau.com/sites/default/files/media/whitepaper_lod_eng_0.pdf

             

            It helps.

             

            S

            • 3. Re: Understanding for LOD
              Michael Gillespie

              Raiyan, think about it like this.

               

              Important first principle: Tableau performs calculations (and other things) with reference to what is in "the view" - in other words, what data elements are on the ROW and COLUMN shelves in the specific worksheet you're dealing with.

               

              What does that mean?  It means that if you are showing, for example, a hierarchy of Category, Sub-Category and Product Name on the ROW shelf(from the Superstore data), and you put SUM(Sales) into the view, Tableau will calculate that sum at the Product Name level.  That's the lowest level of detail in the view at that moment.

               

              What if you don't want that, though?  That's where you use an LOD calculation.  LOD tells Tableau to calculate any aggregation in a very specific way, REGARDLESS of what's in the view.

               

              A FIXED LOD says: Calculate the SUM in a specific way, regardless of what's in the view

              An EXCLUDE LOD says: When you calculate the SUM, DO NOT USE a specific field or fields, EVEN IF they are in the view

              An INCLUDE LOD says: When you calculate the SUM, USE a specific field or fields, EVEN IF they are NOT in the view

               

              Does that help?

              • 4. Re: Understanding for LOD
                meenu choudhary

                Hi Raiyan,

                 

                I can suggest you to go through the below blog. It's having 15 scenarios, and each one are explained very nicely.

                 

                Top 15 Tableau LOD Expressions (Practical Examples)