inspiration and to my family back in India for their unconditional love. My beloved ..... FIGURE 5-9 POWER WHEELCHAIR USABILITY IN RELATION TO USER ...... Data specific to the frequency of purchase and abandonment of past ...... WM by a large number of stakeholders, an online version of the instrument is also being.
DEVELOPMENT OF AN INSTRUMENT TO MEASURE USABILITY OF ASSISTIVE TECHNOLOGY DEVICES
By Sajay Arthanat January 4, 2007 A thesis/dissertation submitted to the Faculty of the Graduate School of the State University of New York at Buffalo in partial fulfillment of the requirements for the degree of Doctor of Rehabilitation Science
Department of Rehabilitation Science School of Public Health and Health Professions University at Buffalo
Usability Scale for Assistive Technology
Copyright by (Sajay Arthanat) (2007) (ii)
ii
Usability Scale for Assistive Technology iii ACKNOWLEDGEMENTS I would like to sincerely thank my advisory committee for their guidance and contribution to this research. I am grateful to my mentor, Dr. Steve Bauer, for always believing in my potential, and for appreciating my research interests and academic qualities in the past five years. Dr. Bauer has played a vital role in conceptualization of my dissertation research and has given me the adequate support to turn this idea into reality. I was also fortunate to have received the mentorship of Dr. James Lenker whose expertise and scholarly skills have been pivotal to my learning in the Rehabilitation Science program. Dr. Lenker’s knowledge and appraisal of assistive technology outcomes research paved my understanding of the importance of this dissertation and its goals. I would also like to extend my gratitude to Dr. Sue Nochajski and Dr. Bill Wu. My long term association with Dr. Nochajski has helped nurture my research skills. I am grateful that she has contributed her time and expertise to every aspect of this research. Dr. Wu’s course on instrument development provided me the impetus to undertake this endeavor and I highly appreciate his guidance on the methodological and statistical aspects of this study. I would like to particularly thank Mr. Douglas Usiak, Executive Director of the Western New York Independent Living Project, for all the assistance his center provided in recruitment of research participants. On the same note, I extend my thanks to Ms. Amy Paily of Aspire Western New York for her help and involvement in this study. I am also indebted to the content reviewers of this instrument for their time and expert review. In addition, I appreciate the assistance of Medha Dharne and Sean Sedacca for review of data collected in the first phase of this study. I would like to also thank my
Usability Scale for Assistive Technology iv supervisors at the Rehabilitation Engineering Research Center for Technology Transfer (T2RERC), Dr. Vathsala Stone- for some of her initial inputs for this research, and Ms. Wendy Strobel- for allotting me the much needed time for its completion. This study was funded by the Mark Diamond Research Fund of University at Buffalo. A special thanks to all the research participants in this study for sharing their experiences and value of assistive technology devices. Personally, I dedicate this dissertation to my late grandmother for her everlasting inspiration and to my family back in India for their unconditional love. My beloved friends in the Rehabilitation Science program and the Association for India’s Development (Buffalo Chapter) have given me the much needed enthusiasm, fun and humor necessary to overcome the pressures of dissertation research. Last but not least, my heartfelt appreciation to my wife, Vidya, for her moral support.
Usability Scale for Assistive Technology v TABLE OF CONTENTS ACKNOWLEDGEMENTS............................................................................................................................ iii LIST OF TABLES ....................................................................................................................................... vii LIST OF FIGURES .................................................................................................................................... viii ABSTRACT ................................................................................................................................................. ix PREFACE ..................................................................................................................................................... 1 CHAPTER I: CONCEPTUALIZATION OF THE USABILITY SCALE FOR ASSISTIVE TECHNOLOGY .. 3 INTRODUCTION ...................................................................................................................................... 3 CONCEPTUAL MODELS OF ASSISTIVE TECHNOLOGY USABILITY................................................ 5 MEASUREMENT OF ASSISTIVE TECHNOLOGY USABILITY ............................................................. 9 INSTRUMENTS RELATED TO USABILITY OF SPECIFIC AT DEVICES ........................................... 12 PROBLEM STATEMENT....................................................................................................................... 15 GOALS OF THE RESEARCH PROGRAM............................................................................................ 18 CHAPTER II: IDENTIFICATION OF MEASUREMENT INDICATORS FOR THE USAT .......................... 20 INTRODUCTION .................................................................................................................................... 20 RESEARCH OBJECTIVES.................................................................................................................... 20 METHODOLOGY ................................................................................................................................... 21 RESULTS ............................................................................................................................................... 25 DISCUSSION ......................................................................................................................................... 27 CHAPTER III: CONSTRUCTION AND CONTENT VALIDATION OF THE USAT-WM ............................ 31 INTRODUCTION .................................................................................................................................... 31 CONTENT VALIDITY: LITERATURE REVIEW..................................................................................... 34 RESEARCH OBJECTIVE ...................................................................................................................... 35 METHODOLOGY ................................................................................................................................... 35 RESULTS ............................................................................................................................................... 38 DISCUSSION ......................................................................................................................................... 39 CHAPTER IV: FIELD TESTING OF THE USAT-WM ................................................................................ 43 INTRODUCTION .................................................................................................................................... 43
Usability Scale for Assistive Technology vi RESEARCH HYPOTHESES.................................................................................................................. 44 METHODOLOGY ................................................................................................................................... 45 RESULTS ............................................................................................................................................... 50 DISCUSSION ......................................................................................................................................... 55 CHAPTER V: USABILITY OF POWER WHEELCHAIRS AS MEASURED BY THE USAT-WM............. 58 INTRODUCTION .................................................................................................................................... 58 BACKGROUND: WHEELED MOBILIY USABILITY............................................................................. 58 THE USABILITY SCALE FOR ASSISTIVE TECHNOLOGY: WHEELED MOBILITY.......................... 62 INTERVENTION FRAMEWORK OF THE USAT-WM...........................................................................64 METHODOLOGY ................................................................................................................................... 66 RESULTS ............................................................................................................................................... 67 DISCUSSION ......................................................................................................................................... 73 IMPLICATIONS ...................................................................................................................................... 76 SUMMARY.................................................................................................................................................. 77 TABLES ...................................................................................................................................................... 83 FIGURES .................................................................................................................................................. 103 APPENDICES........................................................................................................................................... 118 APPENDIX A: PHASE I GENERIC INDICATOR CRITERIA & CHECKLIST ..................................... 118 APPENDIX B: PHASE I INTERVIEW QUESTIONS............................................................................121 APPENDIX C: PHASE I INDICATOR MAPPING AND DISTRIBUTION ............................................ 123 APPENDIX D: CONTENT VALIDATION QUESTIONNAIRE.............................................................. 125 APPENDIX E: INSTITUTIONAL REVIEW BOARD APPROVAL........................................................ 128 APPENDIX F: SUPPORT LETTER FROM WNY INDEPENDENT LIVING PROJECT ...................... 129 APPENDIX G: FINAL VERSION OF THE USAT: WM........................................................................130 REFERENCES.......................................................................................................................................... 139
Usability Scale for Assistive Technology vii LIST OF TABLES TABLE 2-1 EXAMPLES OF CODING PROCESS AND INDICATOR CLASSIFICATION........................ 83 TABLE 2-2 SAMPLING MATRIX FOR THE INTERVIEW ......................................................................... 84 TABLE 2-3 PARTICIPANT CHARACTERISTICS ..................................................................................... 85 TABLE 2-4 SELECTED LIST OF AT USABILITY CRITERIA AND INDICATORS .................................. 86 TABLE 3-1 CONTENT EXPERT DEMOGRAPHICS ................................................................................. 88 TABLE 3-2 USAT-WM: CONTENT VALIDITY INDICES (N=10) .............................................................. 89 TABLE 3-3 RESULTS FROM THE QUALITATIVE ANALYSIS OF REVIEWERS’ COMMENTS............ 90 TABLE 4-1 PARTICIPANT DEMOGRAPHICS (N=65).............................................................................. 91 TABLE 4-2 PRELIMINARY FACTOR ANALYSIS OF USAT-WM SECTIONS......................................... 92 TABLE 4-3 FACTOR ANALYSIS OF THE USAT-WM SUBSCALES....................................................... 94 TABLE 4-4 USAT-WM: INTERNAL CONSISTENCY AND MEAN INTER-ITEM CORRELATIONS........ 96 TABLE 4-5 MEAN SCORES OF USAT-WM, QUEST 2.0 AND PIADS (N=65) ........................................ 97 TABLE 4-6 PEARSON CORRELATIONS: USAT-WM, QUEST & PIADS (N=65) ................................... 98 TABLE 4-7 TEST-RETEST AND ALTERNATE-FORM RELIABILITY OF THE USAT-WM (N=30) ........ 99 TABLE 5-1 PARTICIPANT DEMOGRAPHICS (N=70)............................................................................ 100 TABLE 5-2 WHEELCHAIR CHARACTERISTICS (N=70)....................................................................... 101 TABLE 5-3 USABILITY ISSUES APPLICABLE TO THE USAT-WM INTERVENTION FRAMEWORK102
Usability Scale for Assistive Technology viii LIST OF FIGURES FIGURE 1-1 RELATIONSHIP BETWEEN USER’S FUNCTIONING AND AT USABILITY .................... 103 FIGURE 1-2 THE HUMAN ACTIVITY ASSISTIVE TECHNOLOGY MODEL.......................................... 104 FIGURE 2-1 SATURATION OF USABILITY INDICATORS IN THE INTERVIEW DATA ....................... 105 FIGURE 3-1 CONTENT VALIDITY OF THE USAT-WM (BY SECTION) ................................................ 106 FIGURE 3.2 OVERALL CONTENT VALIDITY OF THE USAT-WM........................................................ 107 FIGURE 4-1 SCATTER PLOT OF TIME1-TIME2 CORRELATION: COMMUNITY SUBSCALE ........... 108 FIGURE 5-1 INTERVENTION FRAMEWORK OF THE USAT-WM ........................................................109 FIGURE 5-2 MEAN SCORES OF USAT-WM SUBSCALES (N=70) ...................................................... 110 FIGURE 5-3 HOME USABILITY OF POWER WHEELCHAIRS.............................................................. 111 FIGURE 5-4 WORKPLACE/SCHOOL USABILITY OF POWER WHEELCHAIRS ................................112 FIGURE 5-5 COMMUNITY USABILITY OF POWER WHEELCHAIRS .................................................. 113 FIGURE 5-6 OUTDOOR USABILITY OF POWER WHEELCHAIRS ......................................................114 FIGURE 5-7 OVERALL USABILITY OF POWER WHEELCHAIRS .......................................................115 FIGURE 5-9 POWER WHEELCHAIR USABILITY IN RELATION TO USER EXPERIENCE (N=70) .... 116 FIGURE 5-9 POWER WHEELCHAIR USABILITY IN RELATION TO WHEELCHAIR DRIVE (N=70) .. 117
Usability Scale for Assistive Technology ix ABSTRACT Usability of assistive technology (AT) devices determines how effectively and efficiently AT users with disabilities can participate in various activities. This research program (dissertation) involved the conceptualization of the Usability Scale for Assistive Technology (USAT), and the development of the Wheeled Mobility module of the USAT, USAT-WM, as a tool to capture user-centered usability of wheeled-mobility devices. In human factors science, usability is considered to be an outcome of the interaction of the user with the product (AT) to accomplish a task (or activity) under the influence of an environment. On this theme, a qualitative inquiry was conducted with users of AT devices focusing on their experiences with use of AT. The interview content was coded and nearly 400 indicators pertaining to wheeled-mobility AT devices were assimilated to construct a preliminary version of the USAT-WM. The content validity of the USAT-WM was evaluated by a panel of clinicians in the field of wheeled-mobility. The findings from the content validation process were utilized to revise the USAT-WM. A field-test of the USAT-WM was conducted by administering it to 70 individuals who used power wheelchairs (PWCs) for mobility. A preliminary principal component analysis of the instrument sections was performed, and based on the item loading a subsequent factor analysis was conducted to establish a 50-item version of the USATWM with seven subscales: home usability; workplace/school usability; community usability; outdoor usability; ease of use; seating; and safety. Internal consistency Cronbach’s alpha values for the seven subscales ranged from 0.77 to 0.91 and 0.90 for the total score of the USAT-WM. The test-retest and alternate-form reliability of the USAT-WM scores correlated at 0.85 (p
