LOD vs table calculations in Tableau - Dashboard Approaches Compared

Dashboard Mode - LOD vs table calculations

Business Question

How can we compare sales performance by category and region using Level of Detail (LOD) expressions versus Table Calculations in Tableau?

Sample Data

Order ID	Category	Region	Sales
1001	Furniture	East	200
1002	Furniture	West	150
1003	Technology	East	300
1004	Technology	West	250
1005	Office Supplies	East	100
1006	Office Supplies	West	120
1007	Furniture	East	180
1008	Technology	West	220

Dashboard Components

• KPI Card: Total Sales
  Formula: SUM([Sales])
  Result: 1720
• Bar Chart: Sales by Category
  Formula: SUM([Sales]) grouped by [Category]
  Results:
  • Furniture: 530
  • Technology: 770
  • Office Supplies: 220
• LOD Calculation Table: Fixed Sales by Category
  Formula: {FIXED [Category]: SUM([Sales])}
  Shows total sales per category ignoring other filters or dimensions
• Table Calculation: Running Total of Sales by Region
  Formula: RUNNING_SUM(SUM([Sales])) computed across [Region]
  Results:
  • East: 780
  • West: 1720
• Cross-tab Table: Sales by Category and Region
  Shows raw sales data summed by both dimensions

Dashboard Layout

+----------------------+-----------------------+
|      KPI Card        |     Bar Chart          |
|  Total Sales: 1720   | Sales by Category     |
+----------------------+-----------------------+
|  LOD Calculation     |  Table Calculation     |
|  Sales by Category   | Running Total by Region|
+----------------------+-----------------------+
|          Cross-tab Table (Sales by Category and Region)          |
+-----------------------------------------------------------------+

Interactivity

Filters on Region and Category apply to all components except the LOD calculation, which always shows total sales by category regardless of filters.

When a user selects a region filter, the Bar Chart, Table Calculation, KPI Card, and Cross-tab Table update to show sales only for that region. The LOD calculation remains fixed.

Self Check

If you add a filter for Region = East, which components update their values?

• KPI Card: Updates to show total sales for East region (680)
• Bar Chart: Updates to show sales by category only for East region
  • Furniture: 380
  • Technology: 300
  • Office Supplies: 100
• LOD Calculation: Does NOT update; still shows total sales by category ignoring region filter
• Table Calculation: Updates running total for East region only (680)
• Cross-tab Table: Updates to show sales by category and East region only

Key Result

Dashboard compares sales by category and region using LOD expressions and table calculations in Tableau.

Practice

1. What is the main difference between LOD expressions and table calculations in Tableau?

easy

A. LOD expressions fix calculations at a specific data level, ignoring some filters, while table calculations work on the data shown in the current view.

B. LOD expressions only work on aggregated data, while table calculations only work on raw data.

C. LOD expressions are faster than table calculations in all cases.

D. Table calculations ignore filters, but LOD expressions depend on the table layout.

Solution

1. Step 1: Understand LOD expressions

   LOD expressions fix the calculation at a certain level of detail, ignoring some filters applied to the view.

2. Step 2: Understand table calculations

   Table calculations work on the data currently displayed in the view and depend on how the table is laid out.

3. Final Answer:

   LOD expressions fix calculations at a specific data level, ignoring some filters, while table calculations work on the data shown in the current view. -> Option A

4. Quick Check:

   LOD fixes level, table calculations depend on view [OK]

Hint: LOD fixes level, table calculations depend on view layout [OK]

Common Mistakes:

• Thinking table calculations ignore filters
• Believing LOD always works on raw data
• Assuming LOD is always faster

2. Which of the following is the correct syntax for a fixed LOD expression in Tableau to calculate total sales per region?

easy

A. { EXCLUDE [Region] : SUM([Sales]) }

B. { INCLUDE [Region] : SUM([Sales]) }

C. { FIXED [Region] : SUM([Sales]) }

D. SUM([Sales]) FIXED BY [Region]

Solution

1. Step 1: Recall fixed LOD syntax

   The fixed LOD syntax is { FIXED [Dimension] : Aggregation }.

2. Step 2: Match syntax to question

   { FIXED [Region] : SUM([Sales]) } matches the correct syntax for total sales per region.

3. Final Answer:

   { FIXED [Region] : SUM([Sales]) } -> Option C

4. Quick Check:

   Fixed LOD uses FIXED keyword and curly braces [OK]

Hint: Fixed LOD always starts with { FIXED ... } [OK]

Common Mistakes:

• Using INCLUDE or EXCLUDE instead of FIXED
• Missing curly braces
• Incorrect keyword order

3. Given a view showing sales by category and sub-category, what will the following LOD expression return?
{ FIXED [Category] : SUM([Sales]) }

medium

A. Total sales for each sub-category ignoring category

B. Total sales for each category repeated for all sub-categories within it

C. Total sales for the entire dataset ignoring category and sub-category

D. Running total of sales by sub-category

Solution

1. Step 1: Understand FIXED by Category

   The expression fixes sales at the category level, ignoring sub-category detail.

2. Step 2: Effect on sub-category rows

   Each sub-category row will show the total sales of its parent category, repeated.

3. Final Answer:

   Total sales for each category repeated for all sub-categories within it -> Option B

4. Quick Check:

   Fixed LOD repeats category total per sub-category [OK]

Hint: Fixed LOD repeats fixed level value for lower detail rows [OK]

Common Mistakes:

• Thinking it sums only sub-category sales
• Confusing FIXED with INCLUDE or EXCLUDE
• Assuming running total behavior

4. You created a table calculation for running total of sales but it shows incorrect results. Which of the following is the most likely cause?

medium

A. The filter is applied before the LOD calculation.

B. The LOD expression used is FIXED instead of INCLUDE.

C. The data source is missing a join condition.

D. The table calculation is not set to compute using the correct dimension.

Solution

1. Step 1: Understand table calculation behavior

   Table calculations depend on the table layout and the dimension used for computation.

2. Step 2: Identify common error

   If the running total is wrong, often the compute using dimension is set incorrectly.

3. Final Answer:

   The table calculation is not set to compute using the correct dimension. -> Option D

4. Quick Check:

   Table calcs need correct compute using dimension [OK]

Hint: Check 'compute using' dimension for table calculations [OK]

Common Mistakes:

• Confusing LOD and table calculation errors
• Blaming data joins for table calc issues
• Ignoring table layout impact

5. You want to show the percent of total sales by region in a view that filters by year. Which approach is best to ensure the percent always reflects all years, ignoring the year filter?

hard

A. Use a FIXED LOD expression to calculate total sales by region ignoring the year filter, then divide sales by this fixed total.

B. Use a table calculation for percent of total sales by region, which automatically ignores filters.

C. Apply the year filter after creating a table calculation for percent of total sales.

D. Use an INCLUDE LOD expression including year to calculate sales.

Solution

1. Step 1: Understand filter impact on calculations

   Table calculations and INCLUDE LOD respect filters, so year filter affects them.

2. Step 2: Use FIXED LOD to ignore year filter

   FIXED LOD can ignore filters like year, fixing total sales by region across all years.

3. Step 3: Calculate percent of total

   Divide sales by the fixed total sales to get percent ignoring year filter.

4. Final Answer:

   Use a FIXED LOD expression to calculate total sales by region ignoring the year filter, then divide sales by this fixed total. -> Option A

5. Quick Check:

   FIXED LOD ignores filters, perfect for fixed percent totals [OK]

Hint: Use FIXED LOD to ignore filters for fixed percent totals [OK]

Common Mistakes:

• Using table calculations that respect filters
• Using INCLUDE LOD which respects filters
• Applying filters after calculations incorrectly