Building Trust in the Sharing Economy : Current Approaches and Future Considerations

This is a self-archived version of an original article. This version may differ from the original in pagination and typographic details. Author(s): Title: Year: Version: Copyright: Rights: Rights url: Please cite the original version: CC BY-NC-ND 4.0 https://creativecommons.org/licenses/by-nc-nd/4.0/ Building Trust in the Sharing Economy : Current Approaches and Future Considerations © 2020 Elsevier Ltd. All rights reserved. Accepted version (Final draft) Räisänen, Jaana; Ojala, Arto; Tuovinen, Tero Räisänen, J., Ojala, A., & Tuovinen, T. (2021). Building Trust in the Sharing Economy : Current Approaches and Future Considerations. Journal of Cleaner Production, 279, Article 123724. https://doi.org/10.1016/j.jclepro.2020.123724 2021 Journal Pre-proof Building Trust in the Sharing Economy: Current Approaches and Future Considerations Jaana Räisänen, Arto Ojala, Tero Tuovinen PII: S0959-6526(20)33769-0 DOI: https://doi.org/10.1016/j.jclepro.2020.123724 Reference: JCLP 123724 To appear in: Journal of Cleaner Production Received Date: 14 January 2020 Revised Date: 31 July 2020 Accepted Date: 10 August 2020 Please cite this article as: Räisänen J, Ojala A, Tuovinen T, Building Trust in the Sharing Economy: Current Approaches and Future Considerations, Journal of Cleaner Production, https://doi.org/10.1016/ j.jclepro.2020.123724. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2020 Published by Elsevier Ltd. Building Trust in the Sharing Economy: Current Approaches and Future Considerations Authors: Jaana Räisänen 1 *, Arto Ojala 2 , Tero Tuovinen 3 Abstract The sharing economy could be an answer to the challenge of sustainability; it can facilitate the sharing and reuse of resources, create new ways of earning money, and enhance social connections. For example, by reducing the use of natural resources without having to acquire or own everything, the sharing economy can positively affect sustainability. At the core of this type of economy lies trust among users and between users and the platform—the system cannot reach its full potential without trust. In fact, businesses or organizations in the sharing economy can even fail due to trust issues, although more information is needed to make better use of the existing platforms. The aim of this systematic literature review is to study how trust is built in the sharing economy. For this purpose, we introduce 28 solutions to support trust in sharing economy platforms, develop a preliminary model for evaluating trust in this context, and present a few considerations for future research. Platform developers and managers can use our preliminary model to identify trust issues in their platforms. Keywords: Sharing economy; Systematic literature review; Sustainability; Trust 1 *Corresponding author. Faculty of Information Technology, University of Jyväskylä, P.O. Box 35, FI-40014 University of Jyväskylä, Finland. Email: [email protected] 2 School of Marketing and Communication, University of Vaasa, PL 700, FI-65101 Vaasa, Finland. Email: arto.oja[email protected] 3 School of Technology, JAMK Jyväskylä University of Applied Science, P.O. Box 207, 40101, Jyväskylä, Finland. Email: [email protected] & Faculty of Information Technology, University of Jyväskylä, P.O. Box 35, FI40014 University of Jyväskylä, Finland. Email: [email protected] Journal Pre-proof Journal Pre-proof 1 Building Trust in the Sharing Economy: Current Approaches and Future Considerations wordcount: 10 401 1. Introduction The world's population is increasing, and this mean an increase in the use of resources. Accordingly, there is a need for solutions to support a more sustainable way of living and doing business. The sharing economy can be one solution for promoting sustainability. The sharing economy enables the use of expensive physical assets without a need to purchase. For example, fashion has a significant environmental impact, and renting or loaning high-end fashion items can reduce the effects on the environment (Zamani et al., 2017). The sharing economy can also make products and assets more affordable (Leung et al., 2019; Schor, 2016) and offer new ways of earning money (Schor, 2016). Further, it can reduce information asymmetry (Thierer et al., 2016; Zloteanu et al., 2018) through digital platforms, be more democratically organized (Schor, 2016), and ecological than traditional businesses (Bocken et al., 2014; Martin et al., 2019). Related to sustainable business models, Bocken et al. (2014) identified different archetypes, such as under-utilized assets and capabilities, market places for second-hand goods, social enterprises, and collaborative models. These archetypes form an important part of the sharing economy. However, whilst the sharing economy certainly provides several benefits, the question remains why it is not more widely used, and why some sharing economy organizations or companies fail. Cohen and Munoz (2016) examined a personalized bus service (named Kutsuplus) that was launched by the city of Helsinki in Finland, which was a hybrid traditional bus service and ride-sharing scheme. The idea seemed good, supported sustainability, and offered a more customized service. However, it failed within the same year, because economic profitability did not rise in line with popularity during the experiment (Kutsuplus-kokeilun loppuraportti, 2016). Another example of a failed scheme is Duara Travels, which was a new kind of travel agency where travelers could stay in villages in developing countries and live with and like local people. The company ensured that all the families and villages engaged in the scheme were safe for tourists and conducted all the marketing and booking. Prices were fair, and host families received 40 % of the payment. Despite seeming effective for supporting responsible tourism in developing countries, Duara Travels failed, as it did not establish a sufficient customer base (Duara Travels, 2020.) The reasons for these failed Journal Pre-proof 2 projects have led several authors to suggest that distrust of companies in the sharing economy (and their services/products) hinders its positive effect and may lead to failures (Chasin et al., 2018; Cherry and Pidgeon, 2018). In other words, by increasing trust toward sharing economy platforms, companies can increase the positive effects and strengthen individuals' decisions to use such platforms (Arteaga-Sánchez et al., 2018; Edbring et al., 2016; Hawlitschek et al., 2018b). Still, the significance and mechanisms of trust development within the sharing economy are largely unexplored (Cohen & Munoz, 2016). To identify the factors that affect trust in sharing economy platforms, we conducted a systematic literature review. More specifically, we aimed to identify 1) how existing studies define the concept of trust, 2) which aspects of trust in the sharing economy have been studied, 3) which technology solutions have been used to build trust in sharing economy platforms, and 4) how to evaluate trust in the sharing economy. By investigating these issues, we aim to clarify the factors that facilitate the building of trust in sharing economy platforms and offer suggestions for future studies on the topic. Moreover, we answer the call by Bijlsma-Frankema and Rousseau (2015) to provide a better overview and synthesis of the existing research on trust. The novelty of this study lies in its collection, comparison, and synthesis of the relevant literature. The paper is structured as follows. The introduction provides the rationale for the study and introduces key vocabulary. Section 2 outlines the research method and explains how the research was conducted. In Section 3, the research findings are presented. In the final chapter, we discuss the results and present conclusions on their significance, practical implications, and future research topics to help other researchers focus on the most relevant issues pertaining to the sharing economy. 1.1 Sharing economy The sharing economy is here to stay. Its economic value has been predicted to grow from US$ 15 billion in 2014 to US$ 335 billion by 2025 (Statista, 2019). For example, the well-known accommodation platform Airbnb made a profit of US$ 93 million in 2017, from total revenues of US$ 2.6 million (Bort, 2018). The sharing economy has been studied to some extent, but defining it remains a subject of debate (Cherry & Pidgeon, 2018). One point of universal agreement is that the sharing economy involves interaction between people (Barnes & Mattson, 2016; Carbone et al., 2018; Future of Money Research Collaborative, 2018; Hou, 2018; Ma et al., 2019), for example, in the context of collaborative consumption it can be seen either as a subset of the sharing economy (Belk, 2014; Hamari et al., 2016) or Journal Pre-proof 3 as a synonym for it (Martin et al., 2019). Terms related to the sharing economy include the gig economy, peer-to-peer economy, on-demand economy (Hou, 2018; Ertz & LeblancProulx, 2018; Future of Money Research Collaborative, 2018; Martin, 2016; Tsui, 2016), access-based consumption, and crowd-based capitalism (Ertz & Leblanc-Proulx 2018). Thus, the taxonomy used to capture the sharing economy is unclear, and the relationships between subsets or terms involved remain vague. The sharing economy can be thought of as a business or supply chain model that uses digital platforms to connect consumers (Hou, 2018). The purposes of these platforms include short-term rentals, ride-sharing, or the sharing of information (Hou, 2018). Schor (2016) suggests that both platforms and the press define who is considered part of the sharing economy. Roos and Hahn (2019, p. 681) propose the following definition: "collaborative consumption is based on the effective management of collaborative, shared use of used, common, or idle resources (i.e., products, assets, or services)." The sharing economy can be divided into four categories: "recirculation of goods, increased utilization of durable assets, exchange of services, and sharing of productive assets" (Schor, 2016, p. 2). Further, it can be categorized according to groups of innovations: 1) accommodation sharing platforms, 2) car and ride sharing platforms, 3) peer-to-peer employment markets, and 4) peer-to-peer platforms for sharing and circulating resources (Martin, 2016). Sharing economy platforms can also be assigned to one of four models: chaperones (prototypical example: Airbnb); franchisers (prototypical example: Uber); gardeners (prototypical example: Couchsurfing); and principals (prototypical example: Handy). Chaperone and franchiser platforms exhibit a high level of rivalry among participants, with loose control by chaperone platform owners compared with tight control exerted by franchiser platform owners. There is low rivalry among participants in gardener platforms, with only loose control used by platform owners. Finally, low rivalry exists among participants in principal platforms, where platform owners exert tight control (Constantiou et al., 2017.) Within the context of this study, we define the sharing economy as a way of sharing a resource (know-how, assets, or information) safely, with or without payment, with other people through a digital platform. Important aspects of this definition are that access to resources is temporary and that sharing happens relatively safely. Usually, the safety of transactions is ensured using technological solutions. 1.2 Trust in the sharing economy Journal Pre-proof 4 The sharing economy is increasing rapidly providing users with certain benefits; however, some crucial aspects remain understudied. In particular, the significance and mechanisms of trust development among the sharing economy are largely unexplored (Cohen & Munoz, 2016). While people have always shared resources, this mainly occurs in interaction with strangers within the sharing economy (Frenken & Schor, 2017). These interactions with unknown parties can be highly risky, potentially resulting in financial and other losses (Luhmann, 2000). Consequently, trust is an essential element within sharing economy platforms, as noted by the Future of Money Research Collaborative (2018). Essentially, trust-based issues within the sharing economy are born out of distrust for old institutions (Lub et al., 2016). Before the industrial era, trust was developed primarily among family members. However, after the industrial revolution, this system was superseded by trust built between strangers through the use of licenses (Hou, 2018). Trust issues in society, such as fundamental distrust (Lub et al., 2016) and trust in the internet economy (Hou, 2018), enabled new kinds of businesses and supply chains to emerge. Recent generations also conceptualize values and attitudes differently: ownership is less important to them than access (Lub et al., 2016). In light of these factors, an accurate understanding of the different aspects affecting trust-building within the sharing economy is essential. This understanding will facilitate the development of better and safer platforms, help inform the public about risks to avoid a false sense of security, assist in the building of better business plans, and promote improved strategic decision-making within the sharing economy. 2. Research Method To conduct a systematic literature review, we followed recommendations by Webster and Watson (2000). Prior systematic literature reviews can be divided into two different types: conventional studies (which may employ meta-analysis) and mapping studies (Kitchenham et al., 2010). This study applies a mapping approach to discover what is known about a certain phenomenon—trust in the sharing economy. By recognizing and categorizing elements that affect trust, we can find ways to better support trust among sharing economy platforms. 2.1 Search process We followed an established protocol to minimize bias in the systematic literature review (Brereton et al., 2007). We first selected the most relevant keywords for the review, Journal Pre-proof 5 which included “trust,” "sharing economy," "peer-to-peer economy," and "gig economy." On initial review of the existing literature, we noted the fragmented nature of available literature. For this reason, we chose not to constrain our scope in the study to any specific journals, research method, or scientific fields. This literature review presents transdisciplinary research in which researchers try to find a "more general and common body of knowledge beyond the disciplines" (Sakao & Brambila-Macias, 2018). Those studies reviewed were from the fields of sustainability, information systems, economics/business, sociology, tourism, and law. The second step was to select relevant databases for the queries. Because of the fragmented nature of the literature, we chose five widely recognized and reliable databases, which we consider to contain a good sample of the sources in terms of breadth and depth, as follows: Academic Search Elite (EBSCO), Science Direct, SAGE Journals Online – SAGE Premier (SAGE), Association for Information Systems Electronic Library (AIS eLibrary), and ProQuest – Science Database (ProQuest). The following research strings were used for the search to find the most relevant literature: trust AND ("sharing economy" OR "peer-topeer economy" OR "gig economy" OR Uber OR Airbnb). Trust was a term used in all the searches because it was a key element. The sharing economy has many subsets and synonyms, which is why "peer-to-peer economy" and "gig economy" were included as search strings. We were also aware that other synonyms such as peer-to-peer rental markets, crowd-based capitalism, on-demand economy, access-based consumption, and collaborative consumption also exist. However, these were discarded as they were rarely used and had little impact on search results. Because the search terms "sharing economy," "peer-to-peer economy," and "gig economy" produced insufficient results in matter of volume, we added the terms Airbnb and Uber. These two platforms have been catalysts for the growing interest in the sharing economy (Martin et al., 2017), and are thought to be dominant platforms (Geissinger et al., 2019). 2.2 Inclusion and exclusion criteria The search was limited to peer-reviewed academic journal articles. We excluded conference publications as their reliability is more challenging to assess. We also set English as a criterion for the language to ensure valid interpretation. Our search was conducted without including any temporal criteria. The keywords were searched mainly from abstracts; however, in some cases, this resulted in very few or no search results. In these cases, the search criteria were expanded to include the body text. This provided more results but often led to results that were outside the research scope. For instance, this was evident in cases Journal Pre-proof 12 The articles in this category (n = 11) considered users' trust in sharing economy platforms or companies. Institutional trust can lead to trust in the sharing economy (Wu & Shen, 2018). For example, with regard to Airbnb, studies suggest that system quality (Wang et al., 2019) and security and privacy (Yang et al., 2018) strongly influence the formation of trust. Personal qualities such as innovativeness (Wang & Jeong, 2018) seem to affect how trustworthy Airbnb is thought to be. However, there are some contradictory research findings: Liang et al. (2018) suggest that trust in Airbnb did not directly affect trust in an individual host; however, Teubner et al. (2019) propose that trust among users may be enhanced because users trust the platform. 3.2.4 Trust as the core of the sharing economy Articles in this category were not as consistent as in other categories, as they considered different aspects or perspectives regarding trust as the core of the sharing economy. Nine articles focused on this area. The sharing economy has its origins in distrust of older more traditional institutions (Lub et al. 2016); thus, trust is essential in this new economic context (Hira, 2017; Leung et al., 2019). For example, Brescia (2016) proposes that the sharing economy would suffer if it were overly regulated. However, the present study found that whilst considering trust as the core of the sharing economy, the articles do not deal with factors that affect trust as such. Instead, they consider why trust is essential to the sharing economy. There is no single solution to enable trust-building. Thierer et al. (2016) indicate that free competition in the market leads to good solutions. Still, these solutions build trust for the platform, not among users (Thierer et al., 2016). The sharing economy is above all an intermediary: it mitigates risks and builds trust (Constantiou et al., 2017). Part of the business model of the sharing economy is to keep prices low, and to do this platforms usually do not offer formal training for service providers, which can lead to a low level of quality control for services (Tauscher & Kietzmann, 2017). Chasin et al. (2018) propose that because sharing economy platforms have weak control over their quality of service, trust and safety are consequently the reasons for their failure. On the contrary, Tsui (2016) asserts that trust is not the cause of business failure. It seems that the research is unanimous about the importance of trust in the sharing economy, but the degree to which it affects the success of a platform remains unclear. 3.3 Different technology solutions to build trust in the sharing economy Journal Pre-proof 13 Based on our review, we found 28 technological solutions thought to build users' trust in sharing economy platforms (or other users), as presented in Table 5. Reputation systems were one of the most studied trust-building solutions. Abrahao et al. (2017) suggest that they can reduce the impact of social bias, for example, through trust in others who are similar (homophily). A study by Rekhiviasvili and Sgibnev (2018) seems to support this: they did not study reputation systems as such but found that technological solutions can compensate for interpersonal trust. Hou (2018) noticed that reputation systems help to build trust between strangers, and the Future of Money Research Collaborative (2018) asserts that reputation has the most powerful impact on users' trust. Reputation not only builds trust but also seems to have a positive effect on sales and prices (ter Huurne et al., 2018). Based on these studies, we can conclude that the use of reputation systems for trust-building among sharing economy platforms is both justified and a good choice; however, these systems are sensitive to small variations. For example, Bente et al. (2014) propose that the difference between three and four stars (rating) is enough to increase sales. As for the question of how technological solutions should be used to best support trust-building, the answer is not so coherent. For example, a study by Zloteanu et al. (2018) suggests that user judgment can be affected by seeing at least three pieces of information relating to trust and reputation; however, it is unaffected by seeing any additional pieces. In turn, Ert et al. (2016) propose that users will use any information they can to make a decision; however, they are unclear about how much trust and reputation information users need to make their decision to trust. Platforms may integrate with social media (Barness & Mattson, 2016). However, they should still maintain their trust and reputation systems because it may be best that trust and reputation information is produced "locally" within the platform (Zloteanu et al., 2018). Thus, it may be that integration with social media should be carefully considered, as it remains unclear whether social media integration supports trust-building among sharing economy platforms. Furthermore, it seems reasonable that information should be generated locally within platforms; otherwise, the purpose of the platforms and their trust systems could result differently making them difficult to compare. Journal Pre-proof 14 Table 5. Technological solutions for building trust. 28 solutions were found from the literature review how trust can be supported in the sharing economy. Technological solution References Background check Amirkiaee & Evangelopoulos, 2018; Etzioni, 2019; Thierer et al., 2015; Xie et al., 2019 Back-up insurance Hawlitschek et al., 2018b; Puschmann & Alt, 2016; Zhu et al., 2018 Big data analytics Thierer et al., 2015 Communication through the platform Bhappu & Schultze, 2018; Thierer et al., 2015 Credit-scoring system for users' self-regulation Lan et al., 2017 Driver's and passengers' dynamic information (location & time) Zhu et al., 2018 Filter for unqualified drivers Zhu et al., 2018 Friend link Molz, 2013 Identity verification De Rivera et al., 2017; Etzioni, 2019; Zhu et al., 2018; Zloteanu et al., 2018; Xie et al., 2019 Informing your friends/family of the car number Kashyap & Bhatia, 2018 Integration with social media Barnes & Mattsson, 2016; Lee et al., 2018 Laws and regulations Bokyeong & Cho, 2016 Number of followers Hou, 2018 Number of reviews Abrahao et al., 2017; Hou, 2018; Zloteanu et al., 2018 Photos De Rivera et al., 2017; Hawlitschek et al., 2018b; Molz, 2013; Xie et al., 2019; Zhang et al., 2018 Profiles/personal information Bhappu & Schultze, 2018; De Rivera et al., 2017; Hawlitschek et al., 2018b; Molz, 2013; Ta et al., 2018; Thierer et al., 2015; Tussyadiah & Park, 2018; Zhang et al., 2018; Zhu et al., 2018 Rating systems Abrahao et al., 2017; Amirkiaee & Evangelopoulos, 2018; Barnes & Mattsson, 2016; De Rivera et al., 2017; Etzioni, 2019; Future of Money Research Collaborative, 2018; Hawlitschek et al., 2018b; Hira, 2017; Hou, 2018; Lee et al., 2018; Thierer et al., 2015; Tsui, 2016; Xie et al., 2019; Zhu et al., 2018; Zloteanu et al., 2018; Reporting of other users' violations of the rules Lan et al., 2017 Reputation systems Abrahao et al., 2017; Bente et al., 2014; Cheng et al., 2019; Costa et al., 2017; Ert et al., 2016; Hou, 2018; Mikołajewska-Zając, 2018; Molz, 2013; ter Huurne et al., 2018; Thierer et al., 2015; Zloteanu et al., 2018 Reviews Amirkiaee & Evangelopoulos, 2018; Chang & Wang, 2018; De Rivera et al., 2017; Hawlitschek et al., 2018b; Kakar et al., 2018; Thierer et al., 2015; Xie et al., 2019; Yang et al., 2018; Zloteanu et al., 2018 Rules and standards Constantiou et al., 2017; Wu et al., 2017 Search function Gleim et al., 2019 Secure payment systems Barnes & Mattsson, 2016; Hawlitschek et al., 2018b; Thierer et al., 2015 Seller information Kakar et al., 2018 Superhost badge Xie & Mao, 2017 Journal Pre-proof 15 Time of departure (Uber & Ola) Kashyap & Bhatia, 2018 Tracking feature (Uber & Ola) Kashyap & Bhatia, 2018 Vouching Molz, 2013 3.4 Evaluating trust in the sharing economy The sharing economy cannot reach its potential without trust. Trust in other users can predict platform usage (Hawlitschek et al., 2018b), is essential for repeated use of the platform (Arteaga-Sánchez et al., 2018), and is a crucial factor affecting the decision to use, for example, ride-sharing (Amirkiaee & Evangelopoulos, 2018). This is why platform developers and companies could use the easy-to-use tool for evaluating user trust. The sharing economy includes for-profit and non-profit organizations, of which non-profit organizations have less money for developing the platform. A lightweight solution could serve such organizations in particular. Based on this comprehensive literature review and its findings, we created a preliminary model (Figure 1) for evaluating users' trust in the sharing economy platform. We aimed to create a tool for sharing economy platform developers/management to use for evaluating user trust. In this paper, we describe our preliminary model from that tool. It has not yet been tested, and its development continues with design science research. We encourage the rest of the academic community to evaluate, test, and further develop this model. We plan to conduct design science research from this subsequently. The tool consists of four sections: 1) platforms' solutions to support the trust of users, 2) trust and interaction between users, 3) users trust for the platform, and 4) users trust for the company/organization. Evaluation occurs with a sliding scale from the center towards the corners. The closer to the center, the less the aspect has been considered within the platform. Measurement can be conducted in practice, for example, with a radar chart (Figure 2) using a scale of 0–5 (where 0 is the aspect that has not been considered at all and five means the element has been considered well). The tool is intended for evaluating user trust in the sharing economy platform and to identify problem areas in relation to trust. If platform developers or managers recognize areas where user trust is not well supported, they can make improvements accordingly. Journal Pre-proof 16 Figure 1. Preliminary model for evaluating users' trust in the sharing economy platform. Figure 2. Example of radar chart based on the preliminary model. 4. Discussion, Future Research Directions, and Limitations 4.1 Discussion and suggestions for further research The sharing economy is forecast to grow significantly (Statista, 2019), and might offer a significant answer to sustainability challenges (Cherry & Pidgeon, 2018). Moreover, trust plays an essential role in the sharing economy (Future of Money Research Journal Pre-proof 17 Collaborative, 2018); therefore, it is crucial to understand it better. We used a systematic literature review to examine the following research questions: 1) How trust is defined in the research? 2) Which aspects of trust within the sharing economy have been studied? 3) Which technology solutions have been employed within the sharing economy? and 4) How can trust in the sharing economy be evaluated? By answering these questions, we learned which essential aspects should be further studied in the future, what should be considered by individuals when trusting others in sharing economy platforms, and what should be taken into account when developing new platforms for the sharing economy. We identified deficiencies in the definition of the term trust in the reviewed articles. Only half (n = 36) of the studies reviewed provided a definition of the concept of trust. This was a somewhat worrisome finding, as it is challenging to investigate the matter with only vague definitions (or no definition at all) for the central term. We recommend that researchers consider which terms require definition, or if the terms are so well-known and universally understood that they can be left without a definition. It would also be wise to review the definition of key terms occasionally, as if an author does not define terms that are ambiguous or difficult to understand, this could lead to difficulties in their comprehension and usage. For example, if we do not know how a researcher has understood a term, it may then be difficult to review the study and compare with similar studies. It should also be noted that research on trust in the sharing economy is multidisciplinary, and, in some fields its application is not particularly intuitive, or the nomenclature of their field is used. We conclude that defining the meaning of trust explicitly is essential to avoid misunderstandings. We hope that these findings will inspire researchers to consider how to define trust in future studies. We also identified that the term sharing economy is understood in slightly different ways. It has synonyms and subsets—for example, gig economy, peer-to-peer economy, and on-demand economy (Hou, 2018; Ertz & Leblanc-Proulx, 2018; Future of Money Research Collaborative, 2018; Martin, 2016; Tsui, 2016)—whose relationships and usage are unclear. The use of these and related terms should be researched and clarified in future. Different fields of study use different terms, which can influence the research framed (Sakao & Brambila-Macias, 2018). If there are no common terms between research fields, it may be hard to create shared knowledge beyond specific research fields. For example, Sakao and Brambila-Macias (2018) argue that the quality of environmental sustainability will benefit from transdisciplinary research. Personal characteristics (for example, personal innovativeness; see Wang & Jeong, 2018) and behaviors (for example, how users portray themselves in a platform; see Journal Pre-proof 18 Tussyadiah & Park, 2018) influence how trustworthy individuals are seen to be within sharing economy platforms. Neither of these has been researched in sufficient depth. For instance, there is a lack of studies focusing on individual social skills and their effect on perceived trustworthiness. For example, digital platforms may discriminate people based on their social skills. Thus, platforms should be developed so that such social bias can be reduced. We already know that individual behavior can either enhance or diminish trust in sharing economy platforms. However, it remains unclear how easily people are able to manipulate other people’s beliefs and create trust under false pretenses. It might be possible to prevent this via specific technological solutions. This would increase equality and support the social dimension of sustainability. Social bias in sharing economy platforms may lead to inequality: personal characteristics and behavior may affect the extent to which individuals can benefit from the sharing economy. Thus, it seems that the sharing economy may impact the social dimension of sustainability in particular. Transparency is often greater in the sharing economy when information is provided not only by the service provider but also by users. Based on this review, there seems to be a shared understanding that trust is the core of the sharing economy, as without trust, there is no sharing. However, the degree to which sharing economy companies take trust into account in their business strategy and their values remains unclear. For instance, whether sharing economy companies understand the importance of trust and how much users' trust affects their success are essential aspects to explore in future studies. Furthermore, we found evidence that user trust in a company can lead users to trust other users (Teubner et al., 2019). Trust among users may have a positive impact on platform usage, and in turn, a positive impact on the success of the platform. This exciting aspect seems to require more attention and studies to refine the contradictory findings related to its importance to companies' performance. For example, Chasin et al. (2018) suggest that "trust and safety are . . . reasons for failures of sharing economy [companies]," while conversely, Tsui (2016) suggests a lack of trust does not seem to be the reason why some sharing economy companies end up failing. Sharing economy businesses do not always exist in a conducive political environment (see, e.g., Zhu, Li, & Zhou, 2018, regarding the Didi ride-hailing platform). For instance, laws and regulations vary from country to country, and regulations can sometimes change at a fast pace—particularly the case for international or global companies, as this may hinder the expansion of a business. Research is therefore required that accounts for and describes the environment in which the sharing economy company operates. For example, geographical Journal Pre-proof 19 area, laws, regulations, and culture should be considered as they can significantly influence the success (or otherwise) of a business. Large, global companies like Airbnb and Uber have been studied extensively, and these studies have provided a great deal of information on trust-building in the sharing economy. However, their large size may lead to a distorted picture of the sharing economy when considering smaller firms and start-ups. In addition, most of these studies have focused on commercial platforms, whereas there seems to be a lack of studies on trust-building within non-commercial operations. Non-commercial and smaller sharing economy platforms could be studied in the future, as their business models and impact of trust on such businesses might differ considerably. We also perceive a need for comparative studies between the sharing economy and traditional business to examine the extent to which technological solutions, personal characteristics, and personal behavior affect trust-building within these two different business models. We further noticed that some researchers (see Martin et al., 2019) say that the sharing economy seems more sustainable than traditional businesses. Still, we did not encounter sufficient evidence to support this. Furthermore, we found that information sharing is an integral part of the sharing economy; however, it is barely addressed in existing studies. A variety of platforms could be taken as a research sample to obtain the broadest possible picture. Other solutions could be to study different kinds of sharing economy platforms separately, and then combine and compare information from these studies with the help of a systematic literature review to gain a broader perspective on the platforms. In this study, we identified 28 different technological solutions for supporting trustbuilding among sharing economy platforms. Many studies supported the use of reputation systems, rating systems, and reviews, but it would be essential to assess which technology solutions are optimal for building trust. The fact that some technological solutions have been used or researched less does not necessarily mean that they are less effective. In addition, there is conflicting information on the optimal number of technological solutions to use. This would be worth researching further, as it is not always economically viable to use multiple solutions. This would help sharing economy companies to be more sustainable by not using funds for something they do not need. A major research topic for the future is to evaluate the impact of the sharing economy on different dimensions of sustainable development, for example see Martin et al. (2019), Schor (2016), and Zervas et al. (2017). There might be a negative environmental impact when sharing economy services are added to traditional products. One example of this is how Journal Pre-proof 20 IKEA in London uses the TaskRabbit sharing economy platform to help customers with product assembly; in this way, they aim to sell more products. However, evaluating the sustainability of the sharing economy is not a simple task. It also has many positive effects; for example, it can increase social connections and employment options (Ciulli & Kolk, 2019). Because the sharing economy is a diverse group of platforms, one way to understand its impact on sustainability could be to view one platform from several different perspectives, such as environmental, economic, social, and cultural points of view. Subsequently, it might be easier to understand how to research the sustainability of the sharing economy on a larger scale. In our literature review, we noted the relatively recent publication of most of the articles. The boundaries of the sharing economy are difficult to draw, and it is still uncertain what economic, ecological, and social impacts the sharing economy will have (Netter et al., 2019). We do not know enough about the sharing economy yet, and questions concerning its content, its effect on sustainability (economic, ecologic, social, and cultural aspects), and how can we support its sustainable aspects are still mostly unanswered or need clarification. 4.2 Implications for theory and practice As Bocken et al. (2014, p. 42) write: "A holistic approach is required to tackle the challenges of a sustainable future: responses to environmental changes will necessarily need to be in parallel with economic and social change." The sharing economy can include environmental, economic, and social aspects of sustainability. In addition, Cherry and Pidgeon (2018) suggest that tackling trust issues should be noted when designing sharing economy concepts and delivery. The sharing economy struggles to find the optimal balance between security, trust, and ease of use. Safetyand trust-related solutions may complicate the use of the assets; whilst at the same time, ease of use is essential, so we should try to understand more about trust-building. This paper presents what we have identified relating to trust in the context of sharing economy. Trust is a remarkable reason why sharing economy platforms fail (Chasin et al. 2018). Based on this literature review, we developed a preliminary model to evaluate the trust of users. This model could especially help small and non-profit sharing economy platforms. For example, Martin et al. (2019) propose that local sharing economy platforms can be more sustainable than traditional businesses. By supporting the development of local, small, and non-profit sharing economy, we can promote sustainability. Journal Pre-proof 21 4.2 Limitations As Kitchenham et al. (2010, p. 804) note regarding systematic literature reviews, "one of the major problems… is finding all the relevant studies." This literature review is no exception, and it should be noted that there might be relevant studies that we did not find in our search. In addition, how we chose our keywords affected the results. Our exclusion criteria might be too limiting, since we excluded conference papers. However, even though this is a limitation, we feel the validity of the study was increased as it can be challenging to evaluate the quality of conferences. Furthermore, in this paper we created a theoretical model of how trust can be assessed in the sharing economy; unfortunately, the model has not yet been tested in practice and requires further empirical validation. In principle, the model is suitable for both research and the development of platforms. The trust research domain is not familiar with the authors. Authors have studied trust before from the perspective of information systems. In this systematic literature review, the field of study was not fixed to only one research field. This can either be a positive feature (for breadth of focus) or conversely it can lead to a fragmented view. This possible limitation should be noted, but the authors still believe that there is a need for this type of research. 5. Summary and Conclusions Trust in the sharing economy has been studied from different perspectives. In this paper, the reviewed studies were divided into four categories: 1) how sharing economy platforms support trust-building, 2) the impact of trust between users on platform usage, 3) users' trust for the sharing economy, and 4) trust as the core of the sharing economy. From the review, 28 technology solutions to build trust were gleaned. Reputation systems, ratings, and reviews were the most used technological solutions for this purpose. Of the 60 papers studied, 24 defined trust, 15 defined it traditionally, and 9 studies defined trust in the digital environment in particular. Of the total of 60 papers, 36 did not define trust at all. Trust in the sharing economy is a current research topic, and most of the studies were written in recent years. It is a critical research topic, because in the future, the sharing economy could be one way to support sustainability. 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PLoS ONE 13(12): e0209071. https://doi.org/10.1371/journal.pone.0209071 Journal Pre-proof Journal Pre-proof Journal Pre-proof Highlights • The sharing economy can support sustainability. • Trust affects the use of the sharing economy • The systematic literature review synthesizes current knowledge of trust in the sharing economy • 28 trust building solutions were recognized • The preliminary model was developed for identifying trust issues in the platform Journal Pre-proof Declaration of interests ☒ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. ☐The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Journal Pre-proof