Level of Detail (LOD) expressions in Tableau allow you to compute values at the data source level and the visualization level, giving you more control over the granularity of your data. LOD expressions are powerful tools for creating complex calculations and aggregations that are not possible with standard calculated fields.

1. Fixed LOD Expressions: Compute values using the specified dimensions, ignoring the view's dimensions.
2. Include LOD Expressions: Compute values using the specified dimensions in addition to the view's dimensions.
3. Exclude LOD Expressions: Compute values using the specified dimensions, excluding certain dimensions from the view.

The general syntax for LOD expressions is:

Scenario: Calculate the total sales per region, regardless of the dimensions in the view.

Code:

Explanation:

• This expression calculates the sum of sales for each region, ignoring any other dimensions in the view.

Scenario: Calculate the average sales per customer within each region.

Code:

Explanation:

• This expression calculates the average sales per customer, including the customer name dimension in addition to the dimensions in the view.

Scenario: Calculate the total sales for each region, excluding the product category dimension.

Code:

Explanation:

• This expression calculates the sum of sales for each region, excluding the product category dimension from the calculation.

Task: Create a fixed LOD expression to calculate the total profit per state, regardless of the dimensions in the view.

Steps:

1. Open Tableau and connect to the Sample - Superstore data source.
2. Create a new calculated field named "Total Profit per State".
3. Enter the following code:

   { FIXED [State] : SUM([Profit]) }
   

4. Drag the "State" dimension to the Rows shelf.
5. Drag the "Total Profit per State" calculated field to the Columns shelf.

Solution:

• You should see the total profit for each state, regardless of any other dimensions in the view.

Task: Create an include LOD expression to calculate the average discount per customer within each region.

Steps:

1. Create a new calculated field named "Average Discount per Customer".
2. Enter the following code:

   { INCLUDE [Customer Name] : AVG([Discount]) }
   

3. Drag the "Region" dimension to the Rows shelf.
4. Drag the "Average Discount per Customer" calculated field to the Columns shelf.

Solution:

• You should see the average discount per customer for each region.

Task: Create an exclude LOD expression to calculate the total sales for each region, excluding the product sub-category dimension.

Steps:

1. Create a new calculated field named "Total Sales per Region Excluding Sub-Category".
2. Enter the following code:

   { EXCLUDE [Sub-Category] : SUM([Sales]) }
   

3. Drag the "Region" dimension to the Rows shelf.
4. Drag the "Total Sales per Region Excluding Sub-Category" calculated field to the Columns shelf.

Solution:

• You should see the total sales for each region, excluding the product sub-category dimension.

• Common Mistake: Misunderstanding the scope of LOD expressions.

  • Tip: Always remember that FIXED ignores the view's dimensions, INCLUDE adds dimensions to the view, and EXCLUDE removes dimensions from the view.

• Common Mistake: Using LOD expressions when a simple calculated field would suffice.

  • Tip: Evaluate whether an LOD expression is necessary for your calculation. Sometimes, a standard calculated field can achieve the same result with less complexity.

Level of Detail (LOD) expressions are a powerful feature in Tableau that allow you to perform complex calculations and aggregations at different levels of granularity. By mastering LOD expressions, you can create more sophisticated and accurate visualizations. In the next section, we will explore creating dashboards, where you can combine multiple visualizations to tell a comprehensive story with your data.