The correct answer is that you must use a dedicated date table marked as a date table in Power BI alongside the SAMEPERIODLASTYEAR function. This is required because time intelligence functions like SAMEPERIODLASTYEAR rely on a continuous, contiguous date range with a proper date hierarchy to perform accurate year-over-year comparison in DAX; without a properly marked date table, the function may return blank or incorrect results due to gaps in the date column. On the Microsoft Power BI Data Analyst PL-300 exam, this question tests your understanding that time intelligence cannot work directly on a fact table’s date column—it needs a separate, continuous date table. A common trap is assuming any date column will work, but the exam emphasizes that the date table must be marked as a date table via the “Mark as Date Table” option. Memory tip: “Time needs a timeline”—always create and mark a dedicated date table before using SAMEPERIODLASTYEAR.
PL-300 Visualize and analyze the data Practice Question
This PL-300 practice question tests your understanding of visualize and analyze the data. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
You are developing a Power BI report to analyze sales performance. The data model includes a 'Sales' fact table with a 'Date' column and a 'Region' dimension table. You need to create a measure that calculates the total sales amount for the current year compared to the previous year. Which TWO of the following steps are required to implement this calculation correctly?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create a separate date table and mark it as a date table in Power BI.
Option B is correct because a dedicated date table marked as a date table in Power BI is required for time intelligence functions like SAMEPERIODLASTYEAR to work correctly. Time intelligence functions rely on a continuous, contiguous date range with a 'Date' column marked as the date table, ensuring accurate year-over-year comparisons. Without this, the functions may return incorrect or blank results due to gaps or non-standard date hierarchies.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 the Quick Measure feature to create a 'Year-over-year change' measure.
Why it's wrong here
Quick measures are optional, not required.
✓
Create a separate date table and mark it as a date table in Power BI.
Why this is correct
Required for time intelligence functions.
Related concept
Read the scenario before looking for a memorised answer.
✗
Apply the CALCULATE function to switch between years.
Why it's wrong here
CALCULATE modifies filter context but is not specific to year comparison.
✓
Use the SAMEPERIODLASTYEAR function in a DAX measure.
Why this is correct
Standard function for previous year comparison.
Related concept
Read the scenario before looking for a memorised answer.
✗
Ensure the 'Sales' table has a relationship to the 'Date' table with a many-to-many cardinality.
Why it's wrong here
Should be many-to-one, not many-to-many.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often think using SAMEPERIODLASTYEAR alone is sufficient, but they overlook the prerequisite of having a separate, marked date table, which is a common requirement tested in PL-300 to ensure time intelligence functions work correctly.
Detailed technical explanation
How to think about this question
Under the hood, SAMEPERIODLASTYEAR shifts the current filter context by exactly one year, relying on the date table's continuous date range and the 'Date' column being marked as the date table. A subtle behavior is that if the date table does not cover the full range of dates in the fact table, SAMEPERIODLASTYEAR may return blank for periods outside the date table's range. In real-world scenarios, failing to mark the date table can cause time intelligence functions to ignore the date hierarchy, leading to incorrect year-over-year comparisons even if the DAX syntax is correct.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Visualize and analyze the data — This question tests Visualize and analyze the data — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Create a separate date table and mark it as a date table in Power BI. — Option B is correct because a dedicated date table marked as a date table in Power BI is required for time intelligence functions like SAMEPERIODLASTYEAR to work correctly. Time intelligence functions rely on a continuous, contiguous date range with a 'Date' column marked as the date table, ensuring accurate year-over-year comparisons. Without this, the functions may return incorrect or blank results due to gaps or non-standard date hierarchies.
What should I do if I get this PL-300 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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