Process Improvement

Question 1

Methodology for monitoring quality of manufacturing and service delivery processes to help identify and eliminate unwanted causes of variation.

Answer 1

Statistical Process Control

Question 2

• result of complex interactions of variations in materials, tools, machines, information, workers, and the environment.
• accounts for 80 to 95 percent of observed variation.
• only management has the power to change systems and infrastructure that cause common cause variation.

ex: amazon distribution center with thousands employees, there will be mistakes.

*on exam, “no way to eliminate it, its to reduce”

Answer 2

Common cause (unassignable) variation

Question 3

• arises from external sources that are not inherent in the process, appear sporadically, and disrupt the random pattern of common causes.
• accounts for 15 to 20 percent of observed variation.
• front line employees and supervisors have the power to identify and solve specific causes of variation.

*on exam

Answer 3

Special (assignable) cause variation

Question 4

Governed only by common cause variation.

Answer 4

Stable system

*on exam

Question 5

No special cause variation affects the output of the process.

Answer 5

In Control System

*on exam

Question 6

When special cause variation is present in the process.

why? you know exactly what or who the problem is and have to fix it.

Answer 6

Out of control

*on exam

Question 7

Higher Special Cause Variation in Structure of a control chart

Answer 7

Upper Control Limit

know how to calculate it

Question 8

Lower Special Cause Variation in Structure of a control chart

Answer 8

Lower Control Limit

know how to calculate

Question 9

• Calculate Range
• Calculate average
• Find mean

Answer 9

Calculating UCL anad LCL

Question 10

Statistical measure of process capability, which measures the ability of a process to produce output within specification limits.

• measures the natural variation in a process that results from common cause variation.
• Cp= measures whether a process is capable when the process mean is centered between the specification limits.
• Cpk= when process capability is not centered, estimates whether the process is in control when the process mean is not centered between the specific limits.

Answer 10

Process capability index

Question 11

know how to calculate it

Upper Specification - Lower specification / 6σ

the higher the Cp, the smaller the variation is

Answer 11

Cp

use when it is centered between the numbers of specification levels

Question 12

min (X-LSL/3σ, USL-X/3σ)

X has the line on top of it

Answer 12

Cpk