Statistical Process Control Flashcards

A Pareto chart in quality improvement is based on which principle?

Answer: 80% of effects come from 20% of causes

The Pareto principle states that roughly 80% of problems stem from 20% of causes, guiding quality teams to prioritize the vital few over the trivial many.

What is the purpose of pre-control charts compared to traditional Shewhart control charts?

Answer: They provide a simpler setup check without requiring historical data

Pre-control charts use specification limits to create zones for quick process setup verification without needing historical process data or calculated control limits.

In a Measurement System Analysis (MSA), 'reproducibility' refers to variation caused by:

Answer: Different operators measuring the same part

Reproducibility measures the variation introduced when different operators use the same instrument to measure the same part, reflecting operator-to-operator inconsistency.

What does the %GR&R statistic evaluate in a gauge R&R study?

Answer: The measurement system variation as a percentage of total process variation

%GR&R expresses measurement system variation (gauge repeatability and reproducibility) as a percentage of total variation, with values under 10% generally acceptable.

Which SPC chart is most appropriate for individual measurements when subgrouping is not practical?

Answer: Individuals and Moving Range (I-MR) chart

The Individuals and Moving Range (I-MR) chart is used when only one measurement is taken at each time point, such as in chemical batch processes or slow production rates.

What does a high kurtosis value in a process distribution suggest about product quality risks?

Answer: The distribution has heavier tails, increasing the likelihood of extreme values

High kurtosis (leptokurtic distribution) means the distribution has heavier tails than a normal distribution, indicating a higher probability of extreme outliers and out-of-spec parts.