DEVELOPMENT OF A SYSTEM FOR COLLECTING AND MAINTAINING

ANTHROPOMETRIC MEASUREMENTS FOR PERSONS WITH DWARFISM


by

BETHANY L. FERGUSON, B.S.


A THESIS

IN

INDUSTRIAL ENGINEERING

Submitted to the Graduate Faculty
of Texas Tech University in
Partial Fulfillment of
the Requirements for
the Degree of

MASTER OF SCIENCE

IN

INDUSTRIAL ENGINEERING


James L. Smith
Chairperson of the Committee


Jeff Woldstad


John Kobza




Fred Hartmeister
Dean of the Graduate School

December 2007

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Texas Tech University, Bethany Ferguson, December 2007
ACKNOWLEDGMENTS

I would like to express my sincerest gratitude to my advisor and committee chair
Dr. James Smith, who has always supported me in my studies and has had such
patience in teaching me. I would never have believed this research was possible
without his encouragement. Many thanks also to Dr. John Kobza who has been
a wonderful professor, supervisor, and friend. I attribute any appreciation I have
of statistics to him. I would also like to thank Dr. Jeff Woldstad who gave me my
first exposure to ergonomics and helped me to realize its potential to impact the
lives of people at work and at home.

I must give special thanks to Little People of America for being such a resource
in my search for information, for confirming the need for this work, and for
allowing me to come to their events to collect data. In addition, I would like to
express many thanks to all the subjects who participated in this research.

Finally, this thesis could not have been accomplished without the support of my
dear family and friends who not only believed I could finish, but also promised to
love me even if I didn’t.



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Texas Tech University, Bethany Ferguson, December 2007
CONTENTS

ACKNOWLEDGMENTS………………………………………………………………ii
ABSTRACT…………………………………………………………………………….v
LIST OF TABLES……………………………………………………………………...vi
LIST OF FIGURES…………………………………………………………………….vii
CHAPTER
1. INTRODUCTION………………………………………………………………..1
1.1 Dwarfism……………………………………………………………………..1
1.2 Anthropometry and Design Philosophy…………………………………..4
1.3 Little People Anthropometry Literature Review………………………….7
1.4 Anthropometry Surveys…………………………………………………..12
1.4.1 Photographic Methods………………………………………….15
2. OBJECTIVES…………………………………………………………………..17
2.1 Little People Anthropometry Survey…………………………………….17
2.2 Little People Anthropometry Database…………………………………17
3. METHODS…………………………………………………………………...18
3.1 Subjects…………………………………………………………………….18
3.2 Procedures…………………………………………………………………19
3.3 Method Validation…………………………………………………………27
4. RESULTS………………………………………………………………………33
4.1 Achondroplasia Subgroup Analysis……………………………………..42
4.2 Sources of Error………………………………………………………...…46
4.3 Posture……………………………………………………………………..47
5. CONCLUSIONS
AND
FUTURE WORK…………………………………….48
5.1
Database…………………………………………………………………...49
REFERENCES…………………………………………………………………………51
APPENDIX A: Access Board Advocacy Data……………………….……………...54
APPENDIX B: TTU Institutional Review Board for the Protection of Human
Subjects Committee Approval Letter……………………………...62
APPENDIX C: Consent Form...……………………………………………………..64
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Texas Tech University, Bethany Ferguson, December 2007
APPENDIX D: Landmark Definition Illustrations.…………………………………..67
APPENDIX E: Method Validation Results…...……………………………………...70
APPENDIX F: Statistical Test Summary Results………………..…………………72
APPENDIX G: Subject Measurement Results……………………………………...75
APPENDIX H: Dimension Distributions for All Subjects (n=49)…………………..83
APPENDIX I: Minitab Measurement Correlations for All Subjects (n=49)…...92
APPENDIX J: Dimension Distributions for Achondroplasia Subjects (n=30)….100
APPENDIX K: Minitab Measurement Correlations for Achondroplasia
Subjects (n=30)…………………………………………………….109


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Texas Tech University, Bethany Ferguson, December 2007
ABSTRACT

Every product or environment a person encounters should match their
capabilities and limitations to maximize safety and efficiency, but the variety
present in the human race makes a design which accommodates everyone
difficult to achieve. It is especially difficult when the user population includes
persons with dwarfism due to their extreme differences in body size and a vast
lack of anthropometric information specific to dwarfs. To aid in achieving
ergonomic design for little people, an anthropometric survey was performed
using photographic methods on forty-nine little people. The analysis of the
results showed that the dimensions were generally normally distributed and
variation was greatly reduced when the subject population was limited to a single
type of dwarfism. The data were used to create models based on highly
correlated measurement pairs so that body measurements could be estimated as
a proportion of total height when anthropometric data were not available. Finally,
recommendations were made on how to improve on the anthropometric survey
method and a database for maintaining current and future measurement data
was proposed.


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Texas Tech University, Bethany Ferguson, December 2007
LIST OF TABLES

1.1: LPA Access Board Study Summary Results……………………………………9
3.1: Method Validation Summary Results…………………………...……………..29
3.2: Confidence Intervals for Dimensions with Equal Variances..….………...31
4.1: Summary Statistics for Anthropometric Dimensions (n=49)…….……..…...33
4.2 Little People Anthropometry Compared to Average-Sized Data…...………..36
4.3 Correlation Coefficients Between Stature and Other Dimensions (n=49)...40
4.4: Seated Dimensions as a Proportion of Stature (n=49)…………...…………..41
4.5: Summary Statistics for Anthropometric Dimensions of Achondroplasia
Dwarfs (n=30).……………..………………………………………..…………...43
4.6: Correlation Coefficients Between Stature and Other Dimensions for
Achondroplasia Subgroup (n=30)………………………...……..…………….44
4.7: Seated Dimensions as a Proportion of Stature for Achondroplasia Subgroup
(n=30)……………………………………………………………………………..46
A.1: Access Board Advocacy Data………………..…………………………………55
E.1: Method Validation Results……………………………..………………………..71
F.1: Statistical Test Summary Results………………………………………………73
G.1: Subject Measurement Results (cm)………………………………..………….76
I.1: Minitab Correlation Results: Pearson Coefficient and P-value (n=49)………93
K.1: Minitab Correlation Results: Pearson Coefficient and P-value (n=30)……110


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Texas Tech University, Bethany Ferguson, December 2007
LIST OF FIGURES

1.1: Stature Distribution and Percentiles……………………..…….……………...6
1.2: Adult Stature Distribution from LPA Database Analysis………..……………...8
1.3: Visual Representation of Anthropometric Measurements Recorded by Kay
Caddel (Caddel 1984)……………………..……………………………………...10
1.4: Scale Representations of Average Measurements (Caddel 1984)
Group I: Achondroplasia Dwarfs Age 0-14
Group II: Achondroplasia Dwarfs Age 14 and up
Group III: Persons of All Ages with Other Types of Dwarfism
……………….………………………………………………………………………11
1.5: Traditional Anthropometric Method Equipment………………………..……...14
1.6: Illustration of Parallax Distortions by Photogrammetric Anthropometry
(Roebuck 1995)…………….……………...…………………………………….15
3.1: Olecranon (elbow) Marker……………………………………………………….20
3.2: Standing Sagittal Plane View, Arm at Side……………………….……………21
3.3: Standing Sagittal Plane View, Elbow at 90°……………………….………..…22
3.4: Standing Frontal Plane View, Anatomical Position…………………..……….24
3.5: Seated Sagittal Plane View…..……………………………………….…………25
3.6: Seated Rear Frontal Plane View………………………………………………..26
4.1: LP Stature Distribution Results (n=49)………………………………...……...34
4.2: Segment Lengths Expressed as a Ratio of Stature from Roebuck, Kroemer,
and Thomson 1975, after Drillis and Contini 1966……………………...……38
4.3: Little People Body Measurement Estimations Based on Proportion of
Stature (n=49)……….…………………………………………...…...….……...41
4.4: Achondroplasia Body Measurement Estimations as a Proportion of
Stature (n=30)……………………………………………………………………45
D.1: Shoulder Definition (Gordon, Churchill, and Clauser 1989)……………...….68
D.2: Toe Definition (Gordon, Churchill, and Clauser 1989)………………….…...68
D.3: Fingertip Definition (Gordon, Churchill, and Clauser 1989)…………………68
D.4: Popliteal Definition (Gordon, Churchill, and Clauser 1989)…………………68
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Texas Tech University, Bethany Ferguson, December 2007
D.5: Knee Definition (Gordon, Churchill, and Clauser 1989)……………………..68
D.6: Ankle Definition (Gordon, Churchill, and Clauser 1989)……………….…….68
D.7: Elbow Definition (Gordon, Churchill, and Clauser 1989)……………….……68
D.8: Heel Definition (Gordon, Churchill, and Clauser 1989)……………….……..68
D.9: Fifth Knuckle Landmark (Gordon, Churchill, and Clauser 1989)…….……..69
D.10: Second Knuckle Landmark (Gordon, Churchill, and Clauser 1989)………69
D.11: Foot Breadth Endpoint 1 (Gordon, Churchill, and Clauser 1989)…………69
D.12: Foot Breadth Endpoint 2 (Gordon, Churchill, and Clauser 1989)…………69
D.13: Head Height Landmark (Gordon, Churchill, and Clauser 1989)…………..69
D.14: Hip Definition (Gordon, Churchill, and Clauser 1989)………………………69
D.15: Wrist Definition (Gordon, Churchill, and Clauser 1989)…………………….69
H.1: Ankle Height Distribution - All Subjects………………………………………..84
H.1: Biacromial Breadth Distribution - All Subjects………………………………...84
H.1: Buttock Breadth Sitting Distribution - All Subjects……………………………84
H.1: Buttock to Popliteal Length Distribution - All Subjects……………………….85
H.1: Elbow Height Distribution - All Subjects……………………………………….85
H.1: Elbow Rest Height Distribution - All Subjects…………………………………85
H.1: Fingertip Height Distribution - All Subjects…………………………………….86
H.1: Foot Breadth Distribution - All Subjects………………………………………..86
H.1: Foot Length Distribution - All Subjects…………………………………………86
H.1: Forearm Length Distribution - All Subjects……………………………………87
H.1: Hand Breadth Distribution - All Subjects………………………………………87
H.1: Hand Length Distribution - All Subjects………………………………………..87
H.1: Hip Breadth Distribution - All Subjects…………………………………………88
H.1: Knee Height Distribution - All Subjects………………………………………...88
H.1: Popliteal Height Distribution - All Subjects…………………………………….88
H.1: Shoulder Height Distribution - All Subjects……………………………………89
H.1: Sitting Height Distribution - All Subjects……………………………………….89
H.1: Sitting Shoulder Height Distribution - All Subjects……………………………89
H.1: Stature Distribution - All Subjects………………………………………………90
H.1: Trochanteric Height Distribution - All Subjects………………………………..90
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Texas Tech University, Bethany Ferguson, December 2007
H.1: Upper Arm Length Distribution - All Subjects…………………………………91
H.1: Wrist Height Distribution - All Subjects………………………………………...91
J.1: Ankle Height Distribution - Achondroplasia Subjects……………………….101
J.1: Biacromial Breadth Distribution - Achondroplasia Subjects……………….101
J.1: Buttock Breadth Sitting Distribution - Achondroplasia Subjects……….….101
J.1: Buttock to Popliteal Length Distribution - Achondroplasia Subjects……...102
J.1: Elbow Height Distribution - Achondroplasia Subjects……………...102
J.1: Elbow Rest Height Distribution - Achondroplasia Subjects………………..102
J.1: Fingertip Height Distribution - Achondroplasia Subjects……………………103
J.1: Foot Breadth Distribution - Achondroplasia Subjects……………………….103
J.1: Foot Length Distribution - Achondroplasia Subjects………………………...103
J.1: Forearm Length Distribution - Achondroplasia Subjects……………………104
J.1: Hand Breadth Distribution - Achondroplasia Subjects………………………104
J.1: Hand Length Distribution - Achondroplasia Subjects……………………….104
J.1: Hip Breadth Distribution - Achondroplasia Subjects………………………...105
J.1: Knee Height Distribution - Achondroplasia Subjects………………………..105
J.1: Popliteal Length Distribution - Achondroplasia Subjects……………………105
J.1: Shoulder Height Distribution - Achondroplasia Subjects……………………106
J.1: Sitting Height Distribution - Achondroplasia Subjects……………………….106
J.1: Sitting Shoulder Height Distribution - Achondroplasia Subjects……………106
J.1: Stature Distribution - Achondroplasia Subjects………………………………107
J.1: Trochanteric Height Distribution - Achondroplasia Subjects……………….107
J.1: Upper Arm Length Distribution - Achondroplasia Subjects…………………108
J.1: Wrist Height Distribution - Achondroplasia Subjects………………………..108



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Texas Tech University, Bethany Ferguson, December 2007
CHAPTER 1
INTRODUCTION

The human race is comprised of people of all colors, shapes, and sizes. This
variety, although beautiful, presents a fundamental challenge for ergonomic
designers who seek to match the capabilities and limitations of the users to their
environment. Physical space requirements and operational biomechanical ability
are two design parameters governed mainly by the user’s physical attributes and
consequently body size has an effect on the design’s usability, comfort, and
efficiency. For example, work surfaces must be at a height that will not strain the
back, emergency shutoff valves must be within reach and easy to operate,
machine guards must block the passage of hands and fingers to safety hazards,
and seat pans must be deep enough to support the thighs and also short enough
to not cut into the back of the legs. The challenge of achieving ergonomic design
is exacerbated by the variety inherent in the user population and results in the
realization that one size does not, in reality, fit all. In fact, demographic surveys
of the United States have shown that two out of every five people are “extra-
ordinary” in some essential aspect (Kroemer 2006). In essence, forty percent of
the population does not conform to the average for some characteristic or
dimension. Some examples of these “extra-ordinary” populations are pregnant
women, children, the disabled, the elderly, and the very small or very large.
These special populations are not considered in designs which use the “average”
human as their reference. This study investigates the dwarf population, their
struggle to fit in an average-sized world, the need for more information on their
size and shape, and the hope for greater accommodation in the future.

1.1 Dwarfism
Dwarfism is one of the oldest and most profound forms of physical difference in
humans; it can be recognized in skeletal remains and diverse cultural
representations throughout history (Ablon 1984). The word dwarfism simply
means stunted growth, but this simple word represents over three hundred
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Document Outline

• Thesis.pdf
• permission to copy.pdf

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