Doctoral Dissertations


"This dissertation develops from quality loss function to warranty loss function in which customer expectation is also considered to be a variable. First, Taguchi's quality loss function for the larger-the-better case, which is different from the smaller-the better and nominal-the-best cases, has been assimilated into the other two by introducing a term called the target-mean ratio. Further topics addressed include the implications of a finite target on the classification of LTB characteristics, a new concept of a "Complementary Characteristic", operating window, complexity, and SN ratio based on complexity. A warranty is a buyer's confidence owing to the seller's assurance to the buyer that a product will perform as stated or implied. The quality loss function only accounts for immediate issues within manufacturing facilities, whereas the warranty cost occurs during customer use. Therefore, this dissertation develops a methodology that can predict warranty probability and warranty costs on the basis of customer expectation in addition to product performance for smaller-the-better, nominal-the-best, and larger-the-better cases. In robust engineering, the signal-to-noise ratio is used to improve the robustness of a system. Most products and processes have multiple quality characteristics or output responses. Therefore, this research has been conducted to propose a metric that can be used for multi-response experiments for minimizing quality loss and improving robustness at the same time. The methodology proposed incorporates all three types of characteristics smaller-the-better, nominal-the-best, and larger-the-better and is based on components of quality loss"--Abstract, page iii.


Ragsdell, K. M.

Committee Member(s)

Drain, David
Midha, A. (Ashok)
Cudney, Elizabeth A.
Myers, Donald D., 1939-2009


Engineering Management and Systems Engineering

Degree Name

Ph. D. in Engineering Management


Missouri University of Science and Technology

Publication Date

Fall 2008

Journal article titles appearing in thesis/dissertation

  • Unification of quality loss function - a unified methodology for three cases
  • Implications of quality loss function in unified methodology - LTB case with target
  • Introduction to warranty loss function on the basis of customer expectation and product performance
  • Warranty loss methodology with other distribution combinations
  • Simultaneous optimization of dynamic multi-response systems using the product of normalized squared-bias and variance


xvii, 221 pages

Note about bibliography

Includes bibliographical references (pages 216-220).

Geographic Coverage

United States


© 2008 Naresh Kumar Sharma, All rights reserved.

Document Type

Dissertation - Open Access

File Type




Subject Headings

Multivariate analysis
Quality control -- Case studies -- Statistical methods
Quality of products -- United States
Taguchi methods (Quality control)

Thesis Number

T 9462

Print OCLC #


Electronic OCLC #