DA0-002 Visualization and Reporting Practice Question
A data analyst has built a dashboard tracking monthly active users (MAU) for a mobile app over the past two years. The executive sponsor complains that the line chart is hard to read because the y-axis starts at zero, making month-to-month variation look small. The analyst wants to emphasize the trend and small fluctuations while still being honest about the data. Which change to the y-axis is most appropriate?
⚠ Common exam trap
The trap here is assuming that any non-zero y-axis is always misleading, when in fact a clearly labeled truncated axis can be appropriate for emphasizing variation.
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
✓
Set the y-axis minimum to a value slightly below the lowest MAU value in the period.
Truncating the y-axis to start just below the lowest value highlights the changes the executive wants to see without falsifying the data. The other options either keep the chart flat, introduce unnecessary complexity, or use scales that obscure the trend. Clear labeling and context are essential when using a non-zero baseline.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Set the y-axis minimum to zero and add a secondary axis showing percentage change.
Why it's wrong here
Keeping the y-axis at zero does not address the sponsor's complaint that variation looks small; the line will still appear flat. Adding a secondary axis for percentage change introduces a different scale and can confuse viewers, and it does not directly solve the visibility of month-to-month fluctuations in the primary metric.
- ✗
Apply a logarithmic scale to the y-axis starting at one.
Why it's wrong here
A logarithmic scale compresses larger values and expands smaller ones, which is useful for exponential growth or wide-ranging data. For MAU that likely varies within a narrow band, a log scale can make the trend harder to interpret and may distort the perceived rate of change, not clarify small fluctuations.
- ✓
Set the y-axis minimum to a value slightly below the lowest MAU value in the period.
Why this is correct
Truncating the y-axis to start slightly below the minimum MAU value magnifies the month-to-month variation, making the trend and fluctuations visible. This preserves the relative shape of the data and is acceptable when the audience understands the axis does not start at zero, as long as it is clearly labeled and not used to mislead.
- ✗
Convert the line chart to a stacked area chart with the y-axis starting at zero.
Why it's wrong here
A stacked area chart is designed to show part-to-whole relationships over time, not a single metric's trend. With only one series, stacking adds no value and can mislead by implying cumulative totals. Starting at zero also fails to amplify variation, so the original readability problem remains.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CompTIA exam blueprint
This DA0-002 practice question is part of Courseiva's free CompTIA 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 DA0-002 exam.