Sensory evaluation is a scientific discipline used to evoke, measure, analyse and interpret responses to products perceived through the senses of sight, smell, touch, taste and hearing. It is used to reveal insights into the way in which sensory properties drive consumer acceptance and behaviour, and to design products that best deliver what the consumer wants. It is also used at a more fundamental level to provide a wider understanding of the mechanisms involved in sensory perception and consumer behaviour. Quantitative Sensory Analysis is an in-depth and unique treatment of the quantitative basis of sensory testing, enabling scientists in the food, cosmetics and personal care product industries to gain objective insights into consumer preference data - vital for informed new product development. Written by a globally-recognised learer in the field, this book is suitable for industrial sensory evaluation practitioners, sensory scientists, advanced undergraduate and graduate students in sensory evaluation and sensometricians.

Quantitative Sensory
Analysis

Harry T. Lawless

This book offers an advanced, quantitative approach to
sensory science problems. Mainstream
sensory evaluation, as practiced in the foods and consumer products industries,
is often primarily concerned with day-to-day tests of pairs of products. Although such testing is often necessary, one
can lose sight of the underlying models and theory for product discrimination
and quantitative description upon which our test procedures and statistical
methods are based.

Sensory evaluation procedures have their roots in classical
psychophysics and statistical methods. Quantitative Sensory Analysis provides a
basis for models underpinning sensory testing for the advanced student and
sensory scientist. Topics that lend
themselves to quantitative analysis such as the theory behind scaling, shelf
life modeling and threshold estimation are treated. The book is not designed as a guide to data
analysis and sensory statistics alone, but treats quantitative modeling in a broader
view. It attempts to gather together all
the quantitative models for sensory phenomena and sensory data in one
work. Rather than focus simply on data
handling issues, the book will have a psychological emphasis, for example, examining
why experimental designs that use panelists as their own controls are often
more powerful for finding product differences.

About the author

Dr Harry T. Lawless
is Professor Emeritus at the Department of Food Science, Cornell University,
Ithaca, New York, USA. His research focuses on perception of taste, smell and
texture in foods and model systems as well as applied research in sensory
testing methods and psychological factors affecting sensory judgments. He supervised the department's sensory
testing facility and was a consultant to
student and faculty projects involving sensory evaluation of foods. Dr Lawless
is the author of the widely adopted textbook Sensory Evaluation of Foods, Principles
and Practices, with Professor Hildegarde Heymann of the University of California,
Davis. He has also served on the editorial boards of Chemical Senses, Chemosensory
Perception, Food Quality and Preference, Journal of the Science of Food and
Agriculture, and the Journal of Sensory Studies.

Also available from Wiley

Product Innovation
Toolbox: A Field Guide to Consumer Understanding and Research
Jacqueline H. Beckley, MBA, Dulce Paredes, Kannapon Lopetcharat / ISBN:
978-0-8138-2397-3

Sensory and Consumer
Research in Food Product Design and Development, 2nd Edition
Howard R. Moskowitz, Jacqueline H. Beckley and Anna V. A. Resurreccion / ISBN:
978-0-8138-1366-0

Sensory Evaluation: A
Practical Handbook
Sarah Kemp, Tracey Hollowood and Joanne Hort / ISBN: 978-1-4051-6210-4

1 Psychophysics I: Introduction and Thresholds 1

1.1 Introduction and Terminology 1

1.2 Absolute Sensitivity 4

1.3 Methods for Measuring Absolute Thresholds 8

1.4 Differential Sensitivity 13

1.5 A Look Ahead: Fechner's Contribution 17

Appendix 1.A: Relationship of Proportions, Areas Under the Normal

Distribution, and Z-Scores 18

Appendix 1.B: Worked Example: Fitting a Logistic Function to Threshold Data 20

References 22

2 Psychophysics II: Scaling and Psychophysical Functions 24

2.1 Introduction 24

2.2 History: Cramer, Bernoulli, Weber, and Fechner 26

2.3 Partition Scales and Categories 27

2.4 Magnitude Estimation and the Power Law 28

2.5 Cross-Modality Matching; Attempts at Validation 32

2.6 Two-Stage Models and Judgment Processes 35

2.7 Empirical Versus Theory-Based Functions 39

2.8 Hybrid Scales and Indirect Scales: A Look Ahead 40

2.9 Summary and Conclusions 41

Appendix 2.A: Decibels and Sones 42

Appendix 2.B: Worked Example: Transformations Applied to Non-Modulus

Magnitude Estimation Data 44

References 45

3 Basics of Signal Detection Theory 47

3.1 Introduction 48

3.2 The Yes/No Experiment 49

3.3 Connecting the Design to Theory 52

3.4 The ROC Curve 57

3.5 ROC Curves from Rating Scales; the R-Index 62

3.6 Conclusions and Implications for Sensory Testing 67

Appendix 3.A: Table of p and Z 68

Appendix 3.B: Test for the Significance of Differences Between d Values 69

References 69

4 Thurstonian Models for Discrimination and Preference 71

4.1 The Simple Paired-Choice Model 71

4.2 Extension into n-AFC: The Byer and Abrams Paradox 78

4.3 A Breakthrough: Power Analysis and Sample Size Determination 80

4.4 Tau Versus Beta Criteria: The SameDifferent Test 84

4.5 Extension to Preference and Nonforced Preference 89

4.6 Limitations and Issues in Thurstonian Modeling 90

4.7 Summary and Conclusions 94

Appendix 4.A: The BradleyTerryLuce Model: An Alternative to Thurstone 95

Appendix 4.B: Tables for delta Values from Proportion Correct 96

References 97

5 Progress in Discrimination Testing 99

5.1 Introduction 99

5.2 Metrics for Degree of Difference 104

5.3 Replication in Choice Tests 108

5.4 Current Variations 110

5.5 Summary and Conclusions 118

Appendix 5.A: Psychometric Function for the Dual Pair Test, Power

Equations, and Sample Size 119

Appendix 5.B: Fun with g 120

References 121

6 Similarity and Equivalence Testing 124

6.1 Introduction: Issues in Type II Error 124

6.2 Commonsense Approaches to Equivalence 126

6.3 Allowable Differences and Effect Size 133

6.4 Further Significance Testing 138

6.5 Summary and Conclusions 140

References 141

7 Progress in Scaling 143

7.1 Introduction 143

7.2 Labeled Magnitude Scales for Intensity 147

7.3 Adjustable and Relative Scales 153

7.4 Explicit Anchoring 155

7.5 Post Hoc Adjustments 158

7.6 Summary and Conclusions 161

Appendix 7.A: Examples of Individual Rescaling for Magnitude Estimation 162

References 164

8 Progress in Affective Testing: Preference/Choice and Hedonic Scaling 167

8.1 Introduction 167

8.2 Preference Testing Options 168

8.3 R…