The goal is to compute an aggregate (SUM(Sales)) at a different, less granular level of detail (Category) than what is displayed in the visualization (Category and Sub-Category). A Level of Detail (LOD) expression is the precise tool for this requirement. The specific calculation, {FIXED [Category] : SUM([Sales])}, instructs Tableau to compute the total sales for each category and return that value for every row belonging to that category, independent of other dimensions like Sub-Category in the view.

A. Quick Table Calculation: Standard quick table calculations, such as running totals or moving averages, operate on the visible data in the view and do not compute aggregates at a fixed, independent level of detail.

B. A Window Function: While a window function like WINDOWSUM(SUM([Sales])) could replicate this result, it is a table calculation. Its output is dependent on the visualization's structure and is less portable than an LOD expression.

D. MAX() Function: The MAX() function is a standard aggregation that would find the single largest sale value. It does not sum values to calculate a total for a category.

1. Tableau Official Documentation

"Create Level of Detail Expressions in Tableau": This document explains the core purpose of LOD expressions. It states

"Level of detail expressions allow you to compute values at the data source level and the visualization level... you can compute aggregations that are not at the level of detail of the visualization." The FIXED keyword is shown to compute a value using only the specified dimensions.

Source: Tableau Help

https://help.tableau.com/current/pro/desktop/en-us/calculationscalculatedfieldslod.htm

2. Tableau Official Documentation

"FIXED Level of Detail Expressions": This page provides a specific example similar to the question. It shows calculating a sum for a region while the view contains states. The syntax {FIXED [Region] : SUM([Sales])} is used to compute the sum of sales at the region level

which is then displayed for each state within that region.

Source: Tableau Help

https://help.tableau.com/current/pro/desktop/en-us/calculationscalculatedfieldslodfixed.htm

Section: "Example 1".

3. Tableau Official Documentation

"Table Calculation Functions": This document details how table calculations

including window functions

operate. It clarifies that these functions compute based on the "virtual table" of data in a visualization

making them dependent on the dimensions present in the view

unlike FIXED LODs.

Source: Tableau Help

https://help.tableau.com/current/pro/desktop/en-us/functionsfunctionstablecalculation.htm

Introduction paragraph.