What are LOD expressions used for in Tableau?

LOD (Level of Detail) expressions in Tableau are designed to control the granularity at which data aggregations are calculated. This allows you to specify different levels of detail in your calculations, independent of the view's level of detail. For example, you can compute averages for different groups (e.g., region, category) while still visualizing data at a higher level such as total sales across all regions. This capability enables more nuanced insights and allows analysts to go beyond standard aggregations that might only consider the dimensions currently in the view.

While summarizing data into a single view might seem related, LOD expressions specifically focus on the depth of data aggregation and how you can calculate values that might not be visually apparent at the current aggregation level. Similarly, cleaning data pertains to data preparation and transformation before visualization and does not directly relate to the granularity of calculations. Lastly, merging datasets from different sources is about data integration rather than the granularity of data aggregation, which is the primary function of LOD expressions.