CQIA Data Collection & Analysis Methods 3 — Questions and Answers
Question 1: Which tool would BEST help a team identify which single defect category to address first to achieve the greatest quality improvement?
- Fishbone diagram
- Pareto chart (Correct answer)
- Scatter diagram
- Control chart
Correct answer: Pareto chart
A Pareto chart ranks defect categories by frequency, visually identifying the vital few that cause the majority of problems.
Question 2: What is the primary purpose of a control chart's upper and lower control limits?
- To set customer specification targets
- To distinguish common cause from special cause variation (Correct answer)
- To display the average defect rate
- To compare two different processes
Correct answer: To distinguish common cause from special cause variation
Control limits define the expected range of process variation; points outside them signal special causes requiring investigation.
Question 3: A quality engineer plots defect counts against production speed and finds r = 0.92. What does this suggest?
- Weak negative correlation between speed and defects
- Strong positive correlation between speed and defects (Correct answer)
- No meaningful relationship exists
- Defects cause increased production speed
Correct answer: Strong positive correlation between speed and defects
A correlation coefficient of 0.92 indicates a strong positive relationship, suggesting defects increase as speed increases.
Question 4: Which data type is BEST analyzed using a p-chart?
- Continuous measurement data like weight
- Proportion of defective items in a sample (Correct answer)
- Count of defects per unit
- Time-between-failure data
Correct answer: Proportion of defective items in a sample
A p-chart monitors the proportion (fraction) of nonconforming items in subgroups of varying or constant size.
Question 5: In the context of data collection, what is operational definition MOST important for?
- Reducing the cost of data collection
- Ensuring consistent measurement and interpretation (Correct answer)
- Selecting the correct sampling frequency
- Automating the data entry process
Correct answer: Ensuring consistent measurement and interpretation
An operational definition specifies exactly what and how to measure so all collectors interpret the criteria the same way.
Question 6: A team reviews a fishbone diagram and identifies five potential root causes. What is the NEXT logical step?
- Implement corrective actions for all five causes simultaneously
- Collect data to verify which causes are actually contributing (Correct answer)
- Close the project since causes have been identified
- Redraw the fishbone with fewer branches
Correct answer: Collect data to verify which causes are actually contributing
After identifying potential causes via a fishbone, data should be collected to confirm which causes are truly driving the problem.
Question 7: Which measure of central tendency is MOST resistant to the effect of extreme outliers?
- Mean
- Median (Correct answer)
- Mode
- Range
Correct answer: Median
The median is the middle value in ordered data and is not distorted by extreme high or low values the way the mean is.
CQIA Data Collection & Analysis Methods 3
Which tool would BEST help a team identify which single defect category to address first to achieve the greatest quality improvement?