Select Measures
The
Quality
Improvement
Model
Define
Process
Select
Measures
Collect &
Interpret
Data
Select Measures
Purpose:
•Develop understanding of
customer needs.
•Determine ‘possible’ process
response control points.
Is
Process
Stable
?
No
Investigate &
Fix Special
Causes
Yes
Improve
Process
Capability
No
Is
Process
Capable
?
Yes
Use SPC to
Maintain
Current
Process
3-1
Select Measures
Importance of Measures
Outputs
Customers
Process
Products or Services
Need Measures of Process Performance

To learn about the process.

To identify improvement
opportunities.

To monitor performance of
the process.
3-2
Select Measures
Use of Measures
Products or Services
Process
Customers
Measurement
Process
Dealing with
the Future
Dealing with
the Past
Process Control
and Improvement
Product Control
and Disposition
What Does This Information
Tell Us About The Process?
Make The Decision
And Move On
3-3
Select Measures
Effective Measures
3-4
Select Measures
Example Measures
Typical Measures of Process Performance
Manufacturing
Product characteristics (weight, dimensions,
color, chemical composition, appearance, etc.),
% not meeting customer specifications, etc.
Administrative
Number of errors, time to complete activity,
percent not meeting requirements, etc.
Service
Service time, delivery time, number of
complaints, etc.
Management
Number of injuries, difference between amount
budgeted & actual expenditures, etc.
3-5
Select Measures
Types of Measures


Counting Measures

Count the number of items that do not
conform to some standard.
Can count
the good
and bad.

Count the number of nonconformities
in a given area, volume, or time
period.
Can count
the bad
only!
Instrument Measures

Quality characteristic is measured by
some type of measuring instrument
(weight, time, size, chemical analysis,
dollars, ...)
3-6
Select Measures
Developing Measures

Understand the customer's needs, expectations, and
wants.

Use process map to identify key points for measures.

Develop & document the measurement process.

Develop a process for collecting, recording, and
analyzing data.

Try the measure.
3-7
Select Measures
Selecting Measures
Outputs
Customers
Process
Products or Services
?
Gauge
In-Process
Gauge
Final Product
Gauge
Customer Satisfaction

Where can we measure the process?

What are pros and cons of the above locations?

Where should we start?
3-8
Select Measures
Process Variables
Suppliers
Inputs
(Raw
Materials)
Process
Outputs
(Product)
Customers
Input Properties Uncontrolled / Response / Output Product
Controlled Variables
Variables
Properties
Process Variables
Process Variables -- All physical or analytical measurements related to a process.
Measurements can be electronic, manual observations, or laboratory results.
Measurements can be in-process or final product oriented.
Process variables can be broken down in to several different types:
•Input Properties - Inputs
•Uncontrolled / Controlled Variables - Inputs
•Response Variables – Outputs (Secondary)
•Product Properties – Outputs (Primary – See on Big Block/SIPOC)
3-9
Select Measures
Input Properties
Inputs
(Raw
Materials)
Suppliers
Process
Outputs
(Product)
Customers
Input Properties Uncontrolled / Response / Output Product
Controlled Variables
Variables
Properties
Process Variables
Input Properties (Inputs)-- Properties of inputs to the process that can be controlled
through contact with supplier.
Examples:
•Manufacturing - Purity of raw materials, composition of mixes, dope solids,
dope viscosity
•Lab - Purity of reagents, brand/model of instrument
•Maintenance - Condition of tools, size/composition of gaskets used in repair
•Administrative - Number of mistakes in data
3-10
Select Measures
Controlled/Uncontrolled Variables
Suppliers
Inputs
(Raw
Materials)
Process
Outputs
(Product)
Customers
Input Properties Uncontrolled / Response / Output Product
Controlled Variables
Variables
Properties
Process Variables
Controlled Variables (Inputs)-- Variables held at a set point or within a range
(standard operating conditions), either manually or by an automatic algorithm (EPC).
Set Point -- The desired level of a controlled variable.
Uncontrolled Variables (Inputs)– Variables that do not have a control system. Can only
be monitored.
Examples:
•Manufacturing - Feed rate of mix, reactor temperature settings (C), outside
temperature (U), pump shaft speed (C), metering pump speed (C)
•Lab - Hot plate temperature setting, time to cook a sample (C)
•Maintenance - Alignment gauge settings, lathe settings (C)
•Administrative - Procedures followed (U)
3-11
Select Measures
Response/Output Variables
Suppliers
Inputs
(Raw
Materials)
Process
Outputs
(Product)
Customers
Input Properties Uncontrolled / Response / Output Product
Variables
Controlled Variables
Properties
Process Variables
Response Variable (Outputs) – an analytical or measured variable that is used to control or
monitor the process but is not a measurement on the final product.
Time Lag -- A delay between expected effects of variables.
Example: 20 minutes after increasing a temperature (controlled input variable), the reactivity
(output variable) begins to increase.
Examples:
•Manufacturing - Composition before distillation, early stage viscosity
•Lab - Visual check for dissolution during heating, final temperature of heated solution
•Maintenance - Vibration of pump during operation, micrometer readings of machined part
•Administrative - Budget variance during the project
3-12
Select Measures
Product Properties / Output Variables
Suppliers
Inputs
(Raw
Materials)
Process
Outputs
(Product)
Customers
Input Properties Uncontrolled / Response / Output Product
Controlled Variables
Variables
Properties
Process Variables
Product Properties (Outputs) -- Measurements made on the final product that indicate its
performance. Important to "Value". Probably will be on Big Block/SIPOC.
Target -- The desired state of a response variable or product property.
Examples:
•Manufacturing - Lab test result on final product (IV, L*, a*, b*, lubricant level, denier,
entanglement)
•Lab - Lab test result on “known” reference material
•Maintenance - Equipment performance in the field, length of time until failure
•Administrative - Number of errors in Certificates of Analysis or purchase orders
3-13
Select Measures
External/Input Variables
External Variables
Inputs
(Raw
Materials)
Suppliers
Process
Outputs
(Product)
Customers
Input Properties Uncontrolled / Response / Output Product
Variables
Controlled Variables
Properties
Process Variables
External Variables (Inputs) -- Variables that are not controlled but may have an
effect on the process. Typically uncontrolled.
Examples:
•Manufacturing - Ambient temperature
•Lab - Humidity
•Maintenance - Vacation scheduling during deer hunting season
•Administrative - Employee morale
3-14
Customer Requirements / Output Variables
Select Measures
External Variables
Suppliers
Inputs
(Raw
Materials)
Process
Outputs
(Product)
Input Properties Uncontrolled / Response / Output Product
Variables
Controlled Variables
Properties
Customers
Customer
Requirements
Process Variables
Customer Requirements (Outputs) -- Fitness-for-use specifications given by the
customer. Will be on Big Block/SIPOC or directly influenced by product property outputs.
Specifications -- the range of measurements of a product characteristic within which the
product is judged acceptable to meet customers’ requirements.
Examples:
•Manufacturing - Purity above 99.7%
•Lab - Sample Value reported within 2 hours
•Maintenance - Repairs completed within 4 hours
•Administrative - Errors below 0.5%
3-15
Select Measures
Three Ways to Control Key Variables in a Process
Control to a
Standard
Statistical
Process
Control
Engineering
Process
Control
3-16
Select Measures
Statistical Process Control (SPC)
•Involves use of control charts, special cause action
plans and control strategies to identify and take action
on special causes.
•Primarily used on response variables and product
properties (outputs).
3-17
Select Measures
Engineering Process Control (EPC)
•EPC moves variation from where it bothers you to
where it doesn’t bother you. (Ex. cruise control)
•Automatically makes compensating adjustments
at a specified frequency.
•Must have reliable measurement, autocorrelated
data, and process adjustments with clear cause &
effect.
•Applied to inputs and outputs
3-18
Select Measures
Control To A Standard
•A standard way to perform a task (S.O.P.).
•A standard range that a key process variable should
be within.
•S.O.P.'s should be audited.
•Primarily used in inputs.
•Fundamental backbone of S.P.C.
•MUST be done first!
3-19