PK0-005 Tools and Documentation Practice Question
A project manager is reviewing a control chart and notices several data points outside the upper control limit (UCL). Which type of variation do these points indicate?
⚠ Common exam trap
PK0-005 often tests the confusion between common cause variation (normal, within limits) and special cause variation (abnormal, outside limits), tempting candidates to pick 'random variation' as a synonym for any unexpected data point.
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
✓
Special cause variation
Data points that fall outside the upper or lower control limits on a control chart signal special cause variation, meaning the variation comes from an assignable, non-random source rather than the normal noise of the process. The control limits (typically set at ±3 sigma from the mean) are specifically designed so that points outside them are statistically unlikely to occur from common cause variation alone. Therefore, points beyond the UCL indicate the process is out of control due to a special (assignable) cause that should be investigated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Common cause variation
Why it's wrong here
Common cause variation is the routine, inherent noise within control limits; points beyond the UCL signal special cause variation instead. It would be the correct answer if the chart showed normal random spread inside the limits, but breaching a limit indicates an assignable, non-routine source.
- ✗
Standard deviation
Why it's wrong here
Standard deviation is a statistical measure of spread, not a category of variation, so it cannot describe out-of-limit points. It would be relevant when calculating control limits themselves, but the question asks which variation type the plotted breaches represent, namely special cause.
- ✗
Random variation
Why it's wrong here
Random variation is ordinary background noise that stays within the control limits; points outside the UCL are statistically unlikely to arise from it. It would be correct for normal process fluctuation, but exceeding a limit indicates special cause variation requiring investigation.
- ✓
Special cause variation
Why this is correct
Points plotting beyond the upper control limit signal that the process is influenced by an assignable, non-random source rather than normal common cause variation. This satisfies the stem's observation of out-of-limit data, indicating special cause variation requiring investigation.
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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 PK0-005 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 PK0-005 exam.