WorksheetsStatistical Process Control (SPC) Quiz
Total questions: 12
Worksheet time: 24mins
What is the primary purpose of Statistical Process Control (SPC)?
To monitor, control, and improve processes by analyzing performance data
To eliminate all variations in a process
To increase production speed
To reduce the number of employees
Who is credited with the development of the control chart?
W. Edwards Deming
Joseph Juran
Walter Shewhart
Kaoru Ishikawa
What is a control chart used for in SPC?
To train employees
To plot process data over time and distinguish between common and special cause variations
To calculate the cost of production
To design new products
What is the difference between common cause and special cause variation?
Both are due to external factors
Both are inherent in the process
Common cause variation is inherent, while special cause variation is due to external factors
Common cause variation is due to external factors, while special cause variation is inherent
What is the main aim of SPC?
To eliminate all defects
To automate the production process
To detect and reduce process variability
To increase the number of products
What type of data do variable data control charts handle?
Data that can be measured on a continuous scale
Categorical data
Binary data
Nominal data
What is the purpose of an X-bar and R chart?
To monitor the mean and range of a process
To track the count of defects per unit
To display the frequency of defects
To monitor the proportion of defective items
How are control limits typically set in SPC?
At four standard deviations above and below the process mean
At three standard deviations above and below the process mean
At two standard deviations above and below the process mean
At one standard deviation above and below the process mean
A factory collected data on the number of nonconforming parts and constructed a p-chart. 15 samples of size 150 were collected. They determined that the average fraction of nonconforming parts was p = 0.037. During production, a sample of 150 parts was taken, of which 11 were nonconforming. At the time this sample was taken:
The sample was within the control limits.
The sample was outside the control limits.
The upper control limit was 0.073.
The lower control limit was -0.01
An X bar and R chart was prepared for an operation using 25 samples with six pieces in each sample. X double bar was found to be 12.68 and s bar was 2.45. During production, a sample of six was taken and the pieces measured 11, 13, 14, 14, 10 and 12. At the time this sample was taken:
Both the average and standard deviation were within the control limits.
Neither the average nor standard deviation were within the control limits.
Only the average was outside the control limits.
Only the standard deviation was outside the control limits.
The diameter of a stainless tell rod is an important quality characteristic. The rod has specifications of 2.50 ± 0.05. Data from the process indicate the distribution is normally distributed, and an X Bar and R chart indicates the process is stable. The control chart used a sample of size 7 and found that X double-bar = 2.5014 and R bar = 0.0568. What is the capability of the process?
0.79
0.77
0.82
0.98
Which of the following is the correct formula to find the specification limits of a quality characteristic?
μ±3σ
x±3 nσ
6σUSL − LSL
Specification limits are determined externally and do not have a generic formula.
