Tableau-Desktop-Found Understanding Tableau Concepts Practice Question
A data analyst is building a view that shows the average shipping cost per order across different ship modes. The data source contains one row per order line item, and orders can have multiple line items. The analyst notices that the average shipping cost is skewed because orders with many line items are overrepresented. Which Tableau feature should the analyst use to calculate the average shipping cost per order correctly?
⚠ Common exam trap
The trap here is assuming that a simple average of a measure will correctly reflect per-order values when the data has a different granularity, ignoring the duplication caused by line items.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use a Level of Detail (LOD) expression with FIXED to calculate the average per order, then aggregate.
The FIXED LOD expression computes the average shipping cost at the order level, ignoring the line-item granularity. This ensures each order contributes equally to the final average. Other methods either operate at the wrong level of detail or fail to deduplicate orders, leading to skewed results.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use a data blend to join the data source to itself on Order ID, then average the shipping cost.
Why it's wrong here
Data blending is used to combine data from different sources, not to resolve duplication within the same source. Blending the source to itself would not remove the line-item duplication and could introduce further complications. It is not the appropriate tool for calculating an average per order when multiple line items exist.
- ✗
Use a regular calculated field with SUM([Shipping Cost]) / COUNT([Order ID]) and set the aggregation to Average.
Why it's wrong here
This calculated field divides total shipping cost by the count of order IDs, but it does not account for the fact that an order with multiple line items will have its shipping cost counted multiple times. The result is still skewed because the numerator sums shipping cost per line item, not per order. It does not correctly compute average per order.
- ✗
Use a table calculation to compute the average shipping cost per order, then filter.
Why it's wrong here
Table calculations operate on the aggregated data in the view, not on the underlying row-level data. They cannot easily compute an average per order when the view is at the line-item level. Using a table calculation would not address the skew caused by multiple line items per order, as it would still be based on the aggregated line-item data.
- ✓
Use a Level of Detail (LOD) expression with FIXED to calculate the average per order, then aggregate.
Why this is correct
An LOD expression with FIXED allows the analyst to compute the average shipping cost at the order level, regardless of the number of line items. This avoids overrepresentation of orders with many line items. The FIXED LOD computes the value at the specified dimension (Order ID), and then the outer aggregation averages those values correctly.
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Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Tableau (Salesforce) exam blueprint
This Tableau-Desktop-Found practice question is part of Courseiva's free Tableau (Salesforce) certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the Tableau-Desktop-Found exam.