Fundamentals Flashcards

A scatter diagram is used in SPC primarily to:

Answer: Explore the relationship between two process variables

A scatter diagram plots pairs of variables to visualize potential correlations or relationships between them.

Which of the following scenarios indicates that a process is 'in statistical control' but NOT 'capable'?

Answer: All points are within control limits but outside specification limits

A process can be stable (in control) yet still produce nonconforming output if its natural spread exceeds the specification range.

The 'R chart' in an X-bar and R control chart monitors:

Answer: The range (spread) within each subgroup

The R chart tracks the within-subgroup range to monitor process variability over time.

In a CUSUM (Cumulative Sum) chart, small persistent shifts in the process mean are detected:

Answer: More effectively than with a Shewhart X-bar chart

CUSUM charts accumulate deviations from the target over time, making them much more sensitive to small, sustained mean shifts than Shewhart charts.

When establishing a new control chart, Phase I analysis refers to:

Answer: Collecting initial data, removing special causes, and calculating baseline control limits

Phase I is a retrospective analysis of historical data used to estimate process parameters and establish initial control limits.

What does a Gauge Repeatability and Reproducibility (Gauge R&R) study evaluate?

Answer: The proportion of total variation attributable to the measurement system

Gauge R&R quantifies how much of the observed process variation is due to the measurement system (equipment and appraiser variation) vs. the actual process.

Which of the following best describes the concept of 'process stability' in SPC?

Answer: The process variation is consistent and predictable over time

A stable process exhibits only common cause variation, making its future behavior statistically predictable.