Research Trends in Mobile Shopping Behavior: A Bibliometric Analysis

The mobile phone, with revolutionary smart capabilities, provided its users enormous benets, especially the convenience of shopping through websites and applications from anywhere and anytime. There are several academic studies conducted to measure the adoption and usage behavior of consumers towards mobile shopping platforms, for more than a decade. However, the research on mobile shopping behavior had gained more attention only in the last few years. The purpose of this study is to conduct a detailed and systematic review of mobile shopping literature (from the consumer behavior perspective) and perform quantitative analysis, with the help of bibliometric analysis. The study examined 158 academic articles that was obtained from Scopus, to perform bibliometric analysis, and the analysis revealed that the research on mobile shopping behavior had gained more attention between 2012 and 2018. The paper identies the key contributions in terms of the most productive journals, countries, institutions, papers, and authors in research on consumers’ mobile shopping behavior. The co-citation reference analysis, keyword co-occurence analysis and word cloud technique had been used, to identify the evolution of various themes focused in this area. This study’s results will make researchers and scholars to have better understanding about the knowledge structure of academic research on mobile shopping through bibliometrics and visualization techniques.


Introduction
The mobile communications technology has undergone drastic changes in the last forty years. Although the mobile network had been introduced in the late seventies of 20 th century, the mobile phones were commercialized only in the early eighties. The signi cant milestones in the history of mobile phones are many including the introduction of GSM features in small screen with limited bene ts, to highly sophisticated, large, and interactive screens resulting in better usage experience via more personalized features. The smartphones, with advanced computing and connectivity, have provided the users with in nite capabilities such as live information, gaming, social networking, shopping, bill payments, and ticketing., and not limited to mere communication features. It is estimated that the total smartphones users worldwide will grow to 3.8 billion by 2021 from 2.5 billion in 2016 (Newzoo, 2019).
Introducing www (world wide web) had created new avenues (including electronic commerce) for businesses, provided with increased opportunities to generate more pro ts at lower costs per order. The e-commerce websites enabled users to order own choice of products and services conveniently from their work/home computers. Despite the Dot-com bubble burst (miserable failure of many e-commerce rms in U.S. because of unrealistic valuations) in the late 1990s, the demand for online shopping had been continued to grow faster (Van Slyke et al. 2002). With advanced (wireless and mobile network) capabilities, the mobile phone had become most signi cant channel for global businesses to provide personalized communication, promote standard and customized products and services, and engage their target customers anytime anyplace. Initially, the mobile shopping was restricted to websites in micro-browsers of mobile phones, until introducing smart applications that resulted in accelerating the users' experience.
There are many reasons for the users' adoption and usage of mobile shopping, which has been studied widely in the academic literature. For instance, a study conducted by Wu et al. (2004) revealed that the three important reasons for choosing a mobile site were the availability of right products (merchandise), enabling functions (for customers to easily search, compare and buy) and assurance (return policies, guarantees for wrong products etc.). Similarly, the intention to use mobile shopping websites was positively affected by users' perceived enjoyment, usefulness and compatibility and negatively affected by their perceived level of anxiety (Lu and Su, 2009). Yang (2010) found that the hedonic or entertainment features of mobile shopping services is an important determinant of consumers' adoption of mobile shopping. The number of research studies that are focusing on the mobile shopping was found to be limited . The users' trust beliefs have been identi ed to be a signi cant factor in uencing the consumers' mobile shopping behavior (Ibid.). The perceived ease of use and satisfaction was found to have a positive in uence on users' intentions to continue using mobile shopping services (Shang and Wu, 2017). Finally, the users' intention to continue using mobile shopping applications and word-of-mouth intention was in uenced strongly by their satisfaction (Sarkar and Khare, 2019). The above discussion, as a preview, have focused on variables related to changing consumer behavior in mobile shopping evolution and development, necessitating the need for systematic review of literature. The purpose of this study is to conduct a detailed and systematic review of mobile shopping literature (from the consumer behavior perspective) and perform quantitative analysis, with the help of bibliometric analysis. This study attempts to ful l the gaps available in the mobile shopping behavior literature i.e. coverage of trends in the mobile shopping behavior and quantitative analysis of research publications such as the number of papers published over the period of time, the most productive journals, and the most in uential research papers. This paper highlights the key developments in the mobile shopping behavior literature, by presenting the quantitative analysis and scienti c mappings of the academic research between 2004 and 2019.

Literature Review
The available academic literature has been covering the various trends and developments of shopping via mobile phones for about 20 years. As this research focuses on consumers' mobile shopping behavior, only review and empirical papers explaining such behavior has been taken into consideration. It was found that various popular theoretical frameworks have been applied in the context of mobile shopping behavior such as TAM (Technology Acceptance Model), TPB (Theory of Planned Behavior), UTAUT (Uni ed Theory of Acceptance and Use of Technology) etc. The analysis of literature has been classi ed into categories based on adoption stage (pre-adoption and postadoption) and shopping platform (mobile sites and mobile applications). The description of the signi cant research papers on mobile shopping literature has been provided in Table 1., based on the above classi cation.

Method
In order to identify various publications for performing bibliometric analysis, the data were extracted from the Scopus database, "a comprehensive, curated abstract and citation database with enriched data and linked scholarly content", with over 24,000 peer reviewed titles from 5,000 publishers across the world (Scopus, 2020). The publications data were collected for the period of 16 years i.e. from 2004 to 2019, by searching with the keywords: "m-shopping", "mobile shopping", "smartphone shopping", "mobile shopping website", "m-commerce", and "mobile shopping application". Only publications (empirical and review), that are focusing on mobile shopping behavior, were included in this study, which resulted in 158 academic articles. The data analysis was performed by using various software applications

Most productive publications
There were more than 90 unique sources on which the study's sample of research articles had been published. Table 2 shows  The CiteScore values highlight the relative importance of journals based on their citation impact. The SCImago Journal and Country Rank (SJR), another important metric available in Scopus, helps researchers to weigh the journals not only based on several citations received but, also the importance or popularity of the journals where the citations come from. The Source Normalized Impact per Paper (SNIP), another important metric, used to measure the contextual citation impact of a journal by weighting citations based on the total number of citations in a subject eld. According to CWTS (Center for Science and Technology Studies), "SNIP corrects for differences in citation practices between scienti c elds, allowing for more accurate between-eld comparisons of citation impact." The CiteScore, SJR, and SNIP value of top-most publication sources are also provided in Table 2  There were totally 30 countries across the world had been contributing to research on mobile shopping behavior. Table   -3 lists the most productive countries in mobile shopping behavior research, with a minimum count of 10 publications, along with other metrics such as total citations, citations per paper and h-index. With 29 publications and 898 citations, the USA had topped the list with the highest score of 30.97 citations per paper and h-index of 17. There are seven papers from USA that had been cited more than 50 times and two of them being cited more than 100 times. Although, the second-most productive country was India with 28 papers, its performance in terms of total citations, total citations per paper and h-index were not satisfactory, implying that most of the research papers did not receive enough attention among the global researchers. The publications in UK were cited 25.70 cites per paper, with three articles having received over 50 citations. The other countries, which made substantial quality of contribution, were Germany, Taiwan, Spain, and South Korea.

Most productive institutions
Although, there were over 100 institutions around the world have published articles in mobile shopping behavior, only few of them had made signi cant contributions in terms of total citations, citations per papers and h-index as given in

Most cited papers
The list of the most signi cant papers in mobile shopping behavior (with a minimum citation of 50) had been presented in Table 5.

Most productive authors
The most in uential and productive author in publishing research on mobile shopping behavior has been listed in Table 6. The top 10 authors with a minimum contribution of three research articles had been considered for analysis. It is found that the total number citations exceeded 50 only for six authors. Kiseol Yang was found to be the most productive and in uential author in mobile shopping behavior in terms of citations per paper, citations per author and placed second in citations per author per year. One more in uential author was Michael Groß, taking a second position in terms of total citations, citations per paper and citations per author, but had got highest score of citations per author per year and h-index.

Co-citation reference analysis
To identify how the research on mobile shopping behavior had been developed and structured over the period, the reference co-citation analysis was done. This study had chosen the references, which had at least 10 citations, thus there were 314 references cited in the mobile shopping research. The visual representation of co-citation networks of the references in mobile shopping behavior is given Fig. 2. From the co-citation network analysis, it is clear there were four clusters (Table 7) formed, and these clusters were provided with suitable names based on most references belonging to them.

Keyword co-occurrence analysis
There was a total of 753 keywords and only ten of them have satis ed the minimum number of occurrence threshold of 10. As given in Fig. 3, there were two clusters formed. The two clusters were named appropriately based on the group of keywords belonging to them (Table 8).
The rst cluster, named as 'Diffusion of e-Commerce', had four keywords namely, electronic commerce, shopping activity, TAM, and technology adoption. The second cluster, labeled as 'Evolution of m-Commerce', contained six keywords, including mobile shopping, m-Commerce, consumer behavior, commerce, mobile telecommunications system, and trust.  The 'Word Cloud', a novel way of representing the key topics in the eld of mobile shopping behavior, by analyzing their patterns and trends, was used in this research. This analysis was performed in Scientopy, an open source scientometric software. The result of word cloud analysis is given in Fig. 4. The keywords, 'Mobile shopping', 'mcommerce', 'Electronic commerce', and 'Consumer behavior' appear bigger than others, meaning that they have been most frequently stated in the literature.

Discussion And Conclusions
The objective of this research study is to shed light on the trends of publications in mobile shopping behavior. From the detailed and systematic review of literature, there are many factors found to measure the consumers' pre-adoption and post-adoption behavior towards mobile shopping, a summary of this is given in Table 9. Since, the previous literature had extensive coverage on various reasons for customers intentions to accept or continue using mobile shopping services, the emerging research areas in mobile shopping behavior need to be identi ed. Most of the studies are cross-sectional in nature, there is a need for conducting longitudinal studies, to measure the dynamic behavior of mobile shoppers (Al-Adwan, 2019). As suggested by Chen et al. (2019), the research on mobile shopper's discontinuance behavior is very limited and need to be studied in different cultural contexts. Mobile shopping applications had become more sophisticated and provide both utilitarian and hedonic bene ts to the shoppers. There is a requirement of more research on how various features of shopping applications such as color, background music, menus, and lighting, would have signi cant effect on shopper's behavior (Lee and Kim, 2019). The review of literature signi ed the need for determining the varying preferences and behavior of shoppers across the product categories like fashion, electronics, groceries etc. As the mobile commerce market is growing with intensi ed competition, there could be motivators and barriers for the mobile vendors to sell various products and services through mobile platforms in various markets (Tan and Ooi, 2018). The question of "How does mobile vendor's market outlook affect the mobile shopper's behavior?" need to be examined. Further, the future research should focus on impact of emerging technologies in the context of mobile shopping behavior. For instance, the integration of Augmented Reality (AR), Virtual Reality (VR), Voice Search, Chatbots, Mobile Image Recognition (MIR) Technology and 5G technology on mobile shopping applications, as this could bring signi cant changes in shoppers' behavior.
The study adopted various bibliometric techniques (citation analysis, co-citation analysis, keyword co-occurence analysis) to examine 158 mobile shopping research papers published between 2004 and 2019. The paper provided a summary of the most productive journals, countries, institutions, papers, and authors in research on consumers' mobile shopping behavior. This analysis offered valuable contributions in understanding the evolution and current state of research on consumers' behavior towards mobile shopping platforms (mobile websites and mobile applications). It was found that majority of the research into this area started in less than a decade and the last ve years witnessed a rapid increase in publications, meaning the growth period of research. The analysis revealed that the Journal of Retailing and Consumer Services was the top-most journal with most publications and the highest number of citations. The most productive country contributing to research on mobile shopping behavior was the United States of America. The Universidad de Burgos, Spain lead the most productive Institution's rankings. The research paper authored by Lu, H.-P., Su, P. Y.-J. had received the highest citations till 2019, and an article written by Wang, R.J.H., Malthouse, E.C., Krishnamurthi, L., had got highest citations per year. Kiseol Yang was found to be the most productive and in uential author in mobile shopping behavior. The co-citation reference analysis, using VOSviewer, uncovered the pillars of theoretical foundations of research on mobile shopping behavior, which resulted in four clusters. These clusters were appropriately named as 'Pre-adoption of Technology', 'Personality Factors', 'Postadoption of Technology' and 'Research Methodology'. The thematic evolution of mobile shopping behavior research had been visualized, using VOSviewer, resulted in two major themes identi ed as 'Diffusion of e-Commerce' and 'Evolution of m-Commerce'. Finally, a unique contribution of this paper is the word cloud, which represents the most frequently used keywords in research on mobile shopping behavior.
The results of this paper have implications for various stakeholders. For academic researchers and scholars, this paper provides valuable insights on choosing the right journals for reference as well as publishing their research work.
It also provides them an overview of most cited papers and authors, co-citation and keyword analysis that could help them in understanding the pillars of theoretical foundations of mobile shopping research. Finally, the emerging research topics in mobile shopping behavior could offer future research directives. The Administrators and Policy makers of Institutions and Nations can have valuable insights from the quantitative analysis of various journals, authors, and institutions to make strategic decisions in improving the quality contributions of their research community. Co-citation analysis of highly cited references used in research papers on mobile shopping behavior