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?

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