Stat 365
Class 1
General Introduction
Key Points
- A process
- is a series of steps or operations that is done repeatedly
- has inputs and outputs
- has customers
- The quality of a process is judged by the value it provides
its customers
- SPC consist of a group of statistical techniques that
can be used to improve processes.
- SPC can be used outside manufacturing on any process
- Deming's fourteen points
- Key idea: Treat work as a process that we should all
collaborate to improve
- Quality and Cost
- Old: Higher quality cost
money:
- More inspection less productivity
- New: Higher quality saves
money
- Do thing right the first time
- Improve the process to improve both quality and reduce
cost
- Management is responsible for 85% of all manufacturing
problems
- Management controls the methods, equipment, material,
environment, and people
- A process is in control if it is subject to only common
causes of variation
- A process is out of control if it is subject to both
common and special causes of variation
- Common causes of variation are inherent to a process.
They affect every iteration of the process
- Special causes of variation are abnormal influence to
a process that lead to erratic or unpredictable behavior. They affect only
some iterations of the process
- A process in control is predictable
- In a control chart points that summarize the behavior
of a process are plotted in time sequence
- Control limits define the amount of variation to be expected
in plotted points if the process is in control.
- When the number defectives or the proportion defective
is plotted the control charts is usually based on the binomial distribution
- When the number of defects or the number of defects per
unit is plotted the control chart is usually based on the Poisson distribution
- When the charts are based on continuous measurements
the normal distribution is usually the basis of the control chart.
Homework Assignments
- Familiarize yourself with this course home page
Study Questions
- What key themes repeat themselves in Deming's fourteen
points?
- What is a process?
- How does one judge the quality of a process?
- What is a control chart?
- What is the difference between a defective and a defect?
Course home
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