Comprehensiveness of Technology acceptance model

        Comprehensiveness refers to the completeness of the information (Cheung & Thadani, 2010, p.335), which implies that the information is understandable and informative and has sufficient breadth and depth (Rabjohn et al., 2008, p.4; Teng et al., 2014, p.748). According to Money et al. (1998), the need to obtain detailed knowledge in decision making process is higher in unfamiliar situation. Money et al. (1998) found that personal relationships are considered as the most efficient information sources, which emphasizes the importance of word of mouth. Consequently, comprehensiveness can be a powerful factor that determines whether consumers buy a product in online environment (Zhao et al., 2015, p.1349). If the information is rich in details as well as has a wide breadth of user categories and user-orientation, the adoption likelihood of that information is higher (Cheung et al., 2008, p.234). Cheung et al. (2008) found that comprehensiveness of online review plays an important role in information adoption because the more comprehensive a review, the more people are willing to adopt it. For the aforementioned reasons, we decided to include comprehensiveness as a key element measuring the information quality in our model.

        Source credibility Recipients of the information can be influenced by peripheral cues such as source credibility (Cheung et al., 2008, p.235). Hovland et al. (1953, p.21), defined source credibility as ‘‘the extent to which a communicator is perceived to be a source of valid assertions’’ and ‘‘the degree of confidence in the communicator’s intent to communicate the assertions he considers most valid’’. In other words, source credibility concerns the degree to which recipients perceive the information source as believable, competent, and trustworthy (Petty & Cacioppo, 1986). Ohanian (1990, p.41) made a further comment that “communicator's positive characteristics affect the receiver's acceptance of a message", meaning that information source features influence the value of communicated information, and thus accelerate the information adoption (Hovland et al., 1953; Ohanian, 1990; Pornpitakpan, 2004; Dou et al., 2012). Consequently, the informational influence of source credibility can change the recipient’s opinions in favour of the opinions advocated by the information source (Cheung et al., 2008, p.232). This alteration will be more significant when the source credibility is high, and adequately less significant when the source credibility is low (Hovland & Weiss, 1951; Hovland et al., 1953). Information that was issued by a highly credible source is perceived as useful and reliable, and thus makes the information transfer easier (Cheung et al., 2008; Ko et al., 2005).

        In respect to Information Adoption Model, source credibility as a peripheral cue plays a significant role in persuasive information process. In order to save time, simplify search and avoid confusion, customers tend to rely on peripheral cues to judge information (Fogg et al., 2003; Metzger, 2007), which emphasize the importance of source credibility for individuals who accept or reject the online source basing on judgement they make (Metzger, et al., 2010; Sundar, 2008). Furthermore, the source credibility may be perceived differently by different individuals, since its perception depends on the receiver's judgement, which consists of the objective evaluation of information quality and accuracy and subjective perception of source credibility (Freeman & Spyridakis, 2004).

        In the context of online reviews, an information source refers to consumers that experienced the product and present an opinion regarding its performance and usage. However, considering the differences in product knowledge level, their opinions might not be seen as credible. Therefore, the credibility is a non-content cue that helps consumers to make a purchase decision (Zhu et al., 2016, p.9-10). Source credibility includes several aspects that when evaluated, show to what extent individuals consider a source to be credible. Two major dimensions of source credibility are expertise and trustworthiness (Hovland et al., 1953; Sussman & Siegal, 2003; Pornopitakpan, 2004; Metzeger, 2007). Expertise describes the degree to which recipients perceive the information source as delivering correct and valid assertions (Hovland et al., 1953) and trustworthiness as the degree of receivers’ confidence that the source provides information that is valid, objective and honest (Hovland et al., 1953; Ohanian, 1991). Another dimension of source credibility, commonly investigated together with expertise and trustworthiness is attractiveness. Source attractiveness describes the degree to which the received information is perceived as appealing (Kiecker & Cowles, 2001) and is able to influence the online user’s information acceptance (Teng et al., 2014, p.749).

        These dimensions of source credibility were selected as the past research showed that source’s trustworthiness, expertise and attractiveness are important factors in influencing consumers’ perception (Cheung et al., 2008). Expertise and trustworthiness are considered the most important components of source credibility (Hovland et al., 1953) and they are shown to have a persuasive effect on consumers’ attitude, behavioural intention and actual behaviour (Senecal & Nantel, 2004, p.161). Another dimension included in this study is attractiveness because it was reported to play a crucial role in persuasion process (Wu & Shaffer, 1987) and affect credibility perceptions of the source (Metzger, 2007). Particularly, attractiveness enhances persuasion when it used as familiarity, similarity and likability (McGuire, 1969; Maddux & Rogers, 1980). Ohanian (1990) was the first to apply expertise, trustworthiness and attractiveness in one study. As attractiveness helps to develop relationships between humans and between humans and organizations, it has a positive influence on customers’ attitude to the source and intention to buy online (Kelman & Eagly, 1965; Haley, 1996, Kiecker & Cowles, 2001; Lee & Yurchisin, 2011). We argue that examining these three dimensions is crucial to determine source credibility and consequently, analyse its impact on purchase intention.