Middlesex University Research Repository An open access repository of Middlesex University research http://eprints.mdx.ac.uk Jamal, Hebah (2019) The perceived trustworthiness of electronic word of mouth (eWOM) on attitude towards dietary supplements, purchase intention and behaviour for dietary supplements amongst female adolescents in Saudi Arabia. PhD thesis, Middlesex University. [Thesis] Final accepted version (with author’s formatting) This version is available at: https://eprints.mdx.ac.uk/26350/ Copyright: Middlesex University Research Repository makes the University’s research available electronically. Copyright and moral rights to this work are retained by the author and/or other copyright owners unless otherwise stated. The work is supplied on the understanding that any use for commercial gain is strictly forbidden. A copy may be downloaded for personal, non-commercial, research or study without prior permission and without charge. 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See also repository copyright: re-use policy: http://eprints.mdx.ac.uk/policies.html#copy Partial Fulfilment 1 The Perceived Trustworthiness of Electronic Word of Mouth (eWOM) on Attitude towards Dietary Supplements, Purchase Intention and Behaviour for Dietary Supplements amongst Female Adolescents in Saudi Arabia By Hebah Jamal Supervised by Dr. Jyoti Navare, Dr. Lorna Wang and Dr. Kailin Wu Middlesex University 2018 Middlesex University Thesis Submitted in the Fulfilment of the Requirements for the Degree of Doctor of Philosophy of Middlesex University Word count 74360 2 Dedication I dedicate this doctoral thesis is to my inspirational mother, my supportive father and my brothers Mohammed and Ahmed, who have always believed that I would reach my goals. Thank you very much for everyone who has been part of my life during this journey. 3 Acknowledgments First and foremost, the Name of the Nameless One, God of everything, the almighty, who enabled me to complete this doctoral thesis and to overcome this challenge in my life. Thank you very much, from the bottom of my heart, to all the people who supported me and cooperated with me during the time I completed my dissertation at Middlesex University. Thanks to MDX University members and students who were so supportive. I would like to sincerely thank my first supervisor, Dr. Jyoti Navare, and my second supervisor, Dr. Lorna Wang. I would like also to thank Dr. Kailin Wu for all her support in this academic journey. Special thanks to my angelic supportive mother, my kind father and my supportive brothers Mohammed and Ahmed. I love you all. 4 Declaration I, Hebah Jamal declare that: • I am the only person responsible for the work submitted in the current thesis. • I wrote this thesis by myself. • All verbatim extracts have been featured and the sources acknowledged. • I submitted some papers during my study period, which are listed below. 1) Jamal, H. K. (2016, June). The role of perceived trustworthiness of eWOM on attitude towards dietary supplements, purchase intentions and behaviour among Saudi female adolescents. Paper presented at the Middlesex University Student Summer Research Conference, Hendon. 2) Jamal, H. K. (2017, November). The conceptual framework and theoretical rationale for the role of perceived trustworthiness of eWOM on attitude towards dietary supplements, purchase intention and behaviour among Saudi female adolescents. Paper presented at the 1st AUE International Research Conference, Dubai. Signature: _________Hebah Jamal___________ Date: _____18-05-2018____________________ 5 Abstract Social networking sites (SNS) such as MySpace, Twitter and Facebook provide effective communication platforms that influence the purchase behaviour of brands for many age groups particularly adolescents. These platforms offer boards of online engagement by user-generated content to share, like and exchange their experience and opinions through electronic word of mouth (eWOM). The aim of this study is to investigate perceived trustworthiness of eWOM dimensions; volume, valence and perceived source expertise of eWOM influence on attitude, purchase intention and purchase behaviour towards dietary supplements amongst Saudi female adolescents. Due to rapid socio-economic changes in Saudi Arabia (SA), healthy food intake was replaced by high-calorie diet and sedentary behaviour. The proposed model for this study investigates purchase behaviour in social media by using the three dimensions of perceived trustworthiness of eWOM. The sample size was 1,027, and a non-probability sampling technique was adopted. The targeted population ranged from 11-19 years old. The covariance-based structural equation modelling (CB- SEM) were performed by using AMOS software. The findings reveal that the perceived trustworthiness of eWOM dimensions show a significant influence on attitude, purchase intention and actual purchase behaviour towards dietary supplements. Interestingly, the perceived body image and time spent on social media do not moderate the relationship between the perceived trustworthiness of eWOM and attitude towards dietary supplements. This study contributes to marketers’ strategy implementation through cooperation with social influencers. In food marketing, labelling should be provided including nutritional facts and re- branding healthy food. Moreover, Policy makers should seriously consider banning fast food from 6 schools and initiating social marketing campaigns. In order to control use of dietary supplements, it should be by prescription only and risk assessments should be introduced as well. Key Words: eWOM, Trustworthiness, Attitude, Purchase Intention, Purchase Behaviour, Dietary Supplement, Female Adolescents, Saudi Arabia, perceived body image, time spent on social media. 7 Table of Contents Abstract ................................................................................................................................ 6 Chapter One: Introduction ................................................................................................... 16 1.1 Introduction .......................................................................................................................... 16 1.2 Background to the Problem ................................................................................................... 16 1.3 Research Rationale ................................................................................................................ 21 1.4 Aims, Objectives and Research Questions ............................................................................. 25 1.4.1 Aim ............................................................................................................................................ 25 1.4.2 Objectives .................................................................................................................................. 25 1.4.3 Research Questions ................................................................................................................... 26 1.5 Expected Research Contributions ......................................................................................... 26 1.5.1 Theoretical Contribution ........................................................................................................... 26 1.5.2 Managerial Contribution ........................................................................................................... 28 1.5.3 Policy Maker Contribution ........................................................................................................ 29 1.6 Chapter summary ................................................................................................................. 29 1.7 Definitions of Constructs and Concepts ................................................................................. 30 1.8 Research structure ................................................................................................................ 34 Chapter Two: Literature Review........................................................................................... 36 2.1 Introduction .......................................................................................................................... 36 2.1.1 Defining WOM ........................................................................................................................... 36 2.1.2 Moving from WOM to eWOM .................................................................................................. 37 2.1.3 eWOM influence on consumer behaviour ...............................................................................