1.  Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall. 12- 1 Chapter 12 Statistically-Based Quality Improvement for Attributes

2.  Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall. 12- 2 Strategic Quality Planning Statistically-Based Quality Improvement for Attributes Chapter 12  Generic process for developing attribute charts  Understanding attribute charts  Reliability models

3.  Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall. 12- 3 Strategic Quality Planning Statistically-Based Quality Improvement for Attributes Generic process for developing attribute charts  Identify Critical Operations  Identify critical product characteristics  Determine whether the product characteristics is a variable or an attribute

4.  Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall. 12- 4 Strategic Quality Planning Statistically-Based Quality Improvement for Attributes Generic process for developing attribute charts  Select the appropriate process chart  Establish control limits  Update the limits when changes have been made to the process

5.  Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall. 12- 5 Strategic Quality Planning Statistically-Based Quality Improvement for Attributes Understanding Attribute Charts  Attribute Charts deal with binomial and Poisson processes, not measurements  Think in terms of defects and defectives rather than diameters and widths

6.  Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall. 12- 6 Strategic Quality Planning Statistically-Based Quality Improvement for Attributes Understanding Attribute Charts  A defect is an irregularity or problem with a larger unit.  The larger unit may contain many defects  Defects are countable

7.  Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall. 12- 7 Strategic Quality Planning Statistically-Based Quality Improvement for Attributes Understanding Attribute Charts  A defective is a unit that, as a whole, is not acceptable or does not meet performance requirements  Defectives are monitored p and np charts  Defects are monitored using c and u charts

8.  Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall. 12- 8 Strategic Quality Planning Statistically-Based Quality Improvement for Attributes Understanding Attribute Charts  A p chart is a process chart that is used the proportion of items in a sample defective  Effective to determine when there has been a shift in the proportion defectives for a particular product or service

9.  Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall. 12- 9 Strategic Quality Planning Statistically-Based Quality Improvement for Attributes Understanding Attribute Charts  p chart applications include:  Late deliveries  Incomplete orders  Calls not getting dial tones  Accounting transaction errors  Parts that do not mate properly

10.  Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall. 12- 10 Strategic Quality Planning Statistically-Based Quality Improvement for Attributes Understanding Attribute Charts  The np chart is a graph of the number of defectives in a subgroup  The np chart requires the sample size of each subgroup be the same  The uses for the np chart are essentially the same as the p chart

11.  Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall. 12- 11 Strategic Quality Planning Statistically-Based Quality Improvement for Attributes Understanding Attribute Charts  The c chart is a graph of the number of defects per unit.  The units must be of the same sample space.. Size, height, length, volume …  The c chart is used to detect nonrandom events in the life of a production process

12.  Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall. 12- 12 Strategic Quality Planning Statistically-Based Quality Improvement for Attributes Understanding Attribute Charts  The u chart is a graph of the average number of defects per unit.  The units can be of different Sizes, height, length, volume …

13.  Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall. 12- 13 Strategic Quality Planning Statistically-Based Quality Improvement for Attributes Reliability Models  Bathtub shaped function  The vertical axis is the failure rate  The horizontal axis is time  Shows products are more likely to fail either early or late in their lifetimes

14.  Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall. 12- 14 Strategic Quality Planning Statistically-Based Quality Improvement for Attributes Reliability Models  Series reliability  Components are in a series if the performance of the entire system depends on all the components functioning properly  The Components need not be physically wired sequentially  All parts must function for the system to function

15.  Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall. 12- 15 Strategic Quality Planning Statistically-Based Quality Improvement for Attributes Reliability Models  Parallel reliability  High reliability systems often require extremely require high component reliability  When it is impossible an alternative is to use a backup system  Another word for backup is redundant or parallel

16.  Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall. 12- 16 Strategic Quality Planning Statistically-Based Quality Improvement for Attributes Summary  The object of using process charts is to continually improve your processes  As we make changes and improvements … there will be fewer defects and defectives

17.  Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall. 12- 17 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. Printed in the United States of America.