CQIA Data Collection & Analysis Methods 2 — Questions and Answers
Question 1: A quality team wants to track the frequency of defect types over a two-week period. Which data collection tool is MOST appropriate?
- Scatter diagram
- Check sheet (Correct answer)
- Control chart
- Affinity diagram
Correct answer: Check sheet
A check sheet is a structured form for collecting and tabulating data about defect frequencies over time.
Question 2: In a histogram, what does a bimodal distribution (two peaks) most likely indicate?
- Random variation in the process
- Two distinct populations or process shifts (Correct answer)
- Data collection errors only
- A process that is in statistical control
Correct answer: Two distinct populations or process shifts
A bimodal histogram typically indicates two distinct subpopulations or process conditions mixed in the data.
Question 3: Which of the following BEST describes stratification as a data analysis technique?
- Ranking defects from most to least frequent
- Separating data into subgroups to identify patterns (Correct answer)
- Plotting data over time to detect trends
- Mapping relationships between two variables
Correct answer: Separating data into subgroups to identify patterns
Stratification divides data into subgroups (e.g., by shift, machine, or operator) to reveal hidden patterns or causes.
Question 4: A Pareto chart is based on which underlying principle?
- All defect types contribute equally to total defects
- A vital few categories account for most of the problems (Correct answer)
- Data must be normally distributed before analysis
- Cause-and-effect relationships are linear
Correct answer: A vital few categories account for most of the problems
The Pareto principle states that roughly 80% of problems come from 20% of causes, guiding focus on the vital few.
Question 5: When constructing a scatter diagram, what does a data point cluster along a positive diagonal indicate?
- No correlation between variables
- A negative correlation between variables
- A positive correlation between variables (Correct answer)
- Seasonal variation in the data
Correct answer: A positive correlation between variables
Points clustering along a positive diagonal show that as one variable increases, the other tends to increase as well.
Question 6: Which sampling method ensures every member of a population has an equal chance of being selected?
- Stratified sampling
- Cluster sampling
- Systematic sampling
- Simple random sampling (Correct answer)
Correct answer: Simple random sampling
Simple random sampling gives every unit an equal and independent probability of selection, eliminating selection bias.
Question 7: A run chart shows seven consecutive data points all above the centerline. What does this pattern signal?
- Normal random variation
- A potential special cause or process shift (Correct answer)
- Measurement system error
- An in-control process
Correct answer: A potential special cause or process shift
Seven or more consecutive points on one side of the centerline is a run rule indicating a likely special cause.
CQIA Data Collection & Analysis Methods 2
A quality team wants to track the frequency of defect types over a two-week period.
Which data collection tool is MOST appropriate?