Statistics Quality Control & Assurance 4

Question 1

In a Double Sampling Plan, what happens if the number of defectives in the first sample falls between the acceptance and rejection numbers?

Accepted Answer

A second sample is drawn and both samples are evaluated together

Answer

In double sampling, an indeterminate first-sample result triggers a second sample; the combined count from both samples is then compared to final acceptance/rejection criteria.

Question 2

Average Outgoing Quality (AOQ) in acceptance sampling reaches its maximum value, called the AOQL, when:

Accepted Answer

The lot fraction defective is at an intermediate level that maximizes the average defective rate after inspection

Answer

AOQ peaks at the AOQL for an intermediate incoming quality level because very good lots are accepted (low defects passed) and very bad lots are rejected and screened (defects removed), but intermediate quality maximizes defects passed.

Question 3

A Pareto chart in quality control is used to:

Accepted Answer

Rank defect types by frequency to identify the vital few causes

Answer

A Pareto chart ranks defect categories in descending frequency, applying the 80/20 rule to focus improvement efforts on the most significant causes.

Question 4

Which control chart should be used when the subgroup size n = 1 (individual measurements)?

Accepted Answer

Individuals (I) and Moving Range (MR) chart

Answer

When only one measurement is taken at each time point, the I-MR chart is used, with the moving range providing an estimate of short-term variation.

Question 5

In the context of Measurement System Analysis, 'reproducibility' refers to:

Accepted Answer

The variation caused by different operators measuring the same part

Answer

Reproducibility is the variation in measurement averages when different appraisers (operators) measure the same set of parts under the same conditions.

Statistics Practice Test

Statistics Practice Test

Statistics Quality Control & Assurance 4