Chapter 8 - Measuring & Controlling Quality (Part 2)

Question 1

How often should Process that are in Control be Monitored?

Answer 1

The process should be monitored with charts daily to check performance, identify any special causes that might arise and make corrections as needed.

Question 2

How are the Lower Control (LCL) and Upper Control (UCL) Limits calculated?

Answer 2

For the Lower Control Limit, the mean is taken and then 3 standard deviations are subtracted to find the limit.

For the Upper Control Limit, the mean is taken and then 3 standard deviations are added to find the limit.

Question 3

Which is easier to understand, Number Nonconforming or Fraction Nonconforming?

Answer 3

Number nonconforming is easier to understand and work with. The sample size must be constant.

Question 4

How do np-Charts differ from p-Charts?

Answer 4

The only difference for np-Charts is scale. The form of the chart will be exactly the same.

Question 5

What do np-Charts calculate?

Answer 5

np-Charts calculate the number of nonconforming units.

Question 6

How are u-Charts used?

Answer 6

u-Charts apply if the samples are of unequal size. They collect samples and count the number of nonconformances.

u-bar computes the average number of nonconformances per unit.

Question 7

Which Control Chart is used when the sample is Variable and more than 10?

Answer 7

X-bar and s-charts

Question 8

Which Control Charts are used when the sample is Variable and more than 1, but less than 10 (and a computer is not available)?

Answer 8

X-bar and R-charts

Question 9

Which Control Charts are used when the sample is Variable and less than 1?

Answer 9

x and moving range charts

Question 10

What are issues of Control Chart Design? (4)

Answer 10

Basis for sampling
Sample Size
Frequency of sampling
Location of control limits

Question 11

Which Control Charts are used for Variables Data?

Answer 11

x-bar and R-charts
x-bar and s-charts
Charts for individuals (x-charts)