SPC Study Guide 2026
Everything you need to pass the SPC exam in one place: the exam format, every topic to study, real practice questions with explanations, flashcards, and full-length practice tests. Free, no sign-up needed.
📚 SPC Topics to Study (31)
✍️ Sample SPC Questions & Answers
1. A process with high Cpk but frequent customer complaints most likely suffers from:
If Cpk is high but complaints occur, the specification limits may be wider than what customers actually need, masking true quality problems.
2. The 'R chart' in an X-bar and R control chart monitors:
The R chart tracks the within-subgroup range to monitor process variability over time.
3. If a process has Cpk = 1.0, what percentage of output is expected to be within specification?
A Cpk of 1.0 corresponds to the process mean being exactly 3 sigma from the nearest specification limit, yielding 99.73% within spec.
4. Which control chart is best suited for monitoring a short-run production environment where part numbers change frequently?
Standardized (Z) charts convert measurements to Z-scores relative to each part's target and tolerance, allowing multiple part types to be plotted on a single chart.
5. A rule of thumb in MSA states that an instrument's resolution should be no greater than what fraction of the process variation or tolerance?
The AIAG MSA Reference Manual recommends that the measurement increment (resolution) should be no larger than one-tenth (1/10) of the process variation or tolerance to avoid masking real differences.
6. A process producing 3.4 defects per million opportunities operates at what sigma level?
Six Sigma quality is defined as 3.4 DPMO, which accounts for a 1.5-sigma long-term shift in the process mean.