An Empirical Study on the Influence of Social Networks and Menu Labeling on Calorie Intake in a University Dining Hall by Dan Wang A Thesis Presented in Partial Fulfillment of the Requirements for the Degree Master of Science Approved May 2014 by the Graduate Supervisory Committee: Carola Grebitus, Chair Christiane Schroeter Mark Manfredo Renee Hughner ARIZONA STATE UNIVERSITY August 2014 ABSTRACT Obesity is a major health problem for both adults and children. It is particularly important for college students to focus on weight management due to weight persistence from adolescent to adult. This study analyzes the influence of peer effects and menu labeling on calorie intake at a university dining hall with posted nutrition facts. Data were collected at the Citrus Dining Hall on Polytechnic Campus of Arizona State University by means of a questionnaire. Groups of four members each were interviewed for a total of 112 individual observations. The results show that individuals who are dining in a group with at least one obese member consume more calories. Also food-related interactions in a group influence the amount of calorie consumption regarding pizza and pasta. Looking at nutrition facts when ordering the food decreases the amount of calories but the effects of menu labeling on calorie intake are not amplified through peer effects. The strength of ties indicated by closeness does not significantly influence calorie intake. There is a need for future research in which more approaches related to social networks need to be tested regarding healthy diets. i DEDICATION I would like to dedicate my thesis to my husband, Bo Li, and my son, Eric Zexin Li. They give me countless support and encouragement and I am sincerely grateful for having them in my life. I also dedicate my thesis to my loving parents. They are the best and supportive parents in the world. Thank you ii ACKNOWLEGEMENTS It would be never possible I can finish my thesis without the guidance of my committee, help from friends and classmates and support from family. I am thankful to Dr. Mark Manfredo for providing an excellent atmosphere for doing my study. I am grateful to Dr. Renee Hughner for giving me encouragement and suggestions. I would like thank to Dr. Christiane Schroeter for her instructive advice and knowledge and many insightful discussions and suggestion. I would like to express my deepest gratitude to my committee chair, Dr. Carola Grebitus. The whole study started with her inspiration and ended up with a completed thesis with her patient and selfless guidance and help. Her remarkable mentoring not only guides me throughout this thesis, but also benefits my rest of life for pursuing my career in marketing analysis. I also thank my friend, Liling Yan and Yi Xie. I would not be able to persist to my study without their encouragement and help. I would like to thank my parents, my husband and my son for their unconditional supporting and encouraging throughout the thesis. Finally, I am forever grateful to the Morrison School for letting me have opportunity to get ready to meet all challenges in my life. iii TABLES OF CONTENTS Page LIST OF TABLES ................................................................................................................. vi LIST OF FIGURES .............................................................................................................. vii INTRODUCTION .................................................................................................................. 1 Background ................................................................................................................... 1 Research Objectives and Hypotheses .......................................................................... 4 BACKGROUND INFORMATION ...................................................................................... 5 Healthy Weight, Overweight, Obesity and Body Mass Index .................................... 5 Dietary Guidelines ........................................................................................................ 6 Menu Labeling .............................................................................................................. 7 Social Network Analysis .............................................................................................. 8 Social Influence and Social Proximity ......................................................................... 9 Degree Centrality ........................................................................................................ 11 Strength of Ties .......................................................................................................... 13 LITERATURE REVIEW ..................................................................................................... 15 Individual Calorie Estimation .................................................................................... 15 Menu Labeling and Food Choice ............................................................................... 15 Peer Effects and Food Choice .................................................................................... 18 METHODS ............................................................................................................................ 20 Study Design ............................................................................................................... 20 Questionnaire .............................................................................................................. 21 iv Page Data Collection for Calorie Intake ............................................................................. 22 Social Network Analysis: Contact Frequency, Closeness and Strength of Ties ...... 23 Analysis of Menu Labeling and Food Choice ........................................................... 24 Analysis of Calorie Intake and Calorie Estimation ................................................... 25 Analysis of Interactions during the Lunch ................................................................. 26 Econometric Analysis: Tobit Model .......................................................................... 28 EMPIRICAL RESULTS ....................................................................................................... 32 Descriptive Statistics .................................................................................................. 32 Sample Characteristics ................................................................................... 32 Social Network of Dining Hall Patrons ......................................................... 36 Food Preference, Food Choice and Menu Labeling ..................................... 40 Calorie Intake ................................................................................................. 47 Calorie Estimation.......................................................................................... 49 Interactions during the Lunch ........................................................................ 51 Model Results and Discussion ................................................................................... 54 CONCLUSION ...................................................................................................................... 61 REFERENCES ..................................................................................................................... 64 APPENDICIES A SURVEY INSTRUMENT ........................................................................................... 71 B MENU AND CALORIES TABLE .............................................................................. 79 C STRENGTH OF TIES AND STRENGTH OF LUNCH TIES FOR 28 GROUPS ... 83 v Page D SURVEY APPROVAL ..................................................................................................... 85 vi LIST OF TABLES Table Page 1. BMI Categories ............................................................................................................. 6 2. Examples of the Basic Shape of Networks .................................................................. 9 3. Characteristics of the Study Sample ........................................................................... 33 4. Social Demographics vs. BMI Categories ................................................................. 36 5. Contact Frequency via Four Channels, Dining Frequency, and Closeness .............. 37 6. Social Demographics vs. Self-reported Impact of Menu Labelng’influences on Food Choice ........................................................................................................................... 44 7. Calorie Intake at the Dining Hall ................................................................................ 48 8. Perceived Healthy Value and BMI Categories vs. Calorie Intake Categories .......... 48 9. Comparison between Actual Calories and Estimated Calories for 7 Meals ............. 50 10. In-degree and Out-degree in Notice 1 and Notice 2 .................................................... 52 11. Peers’ Interactions during the Lunch in terms of In-degree and Out-degree .............. 53 12. Influence of Peers’ Obesity Status, Nutrition Labeling, Social Interactions on the Calorie Intake from Pizza & Pasta ............................................................................. 56 13. Influence of Peers’ Obesity Status, Nutrition Labeling, Social Interactions and Strength of Ties on the Calore Intake from Pizza & Pasta ........................................