The Four Types of Web Credibility

The Four Types of Web Credibility

The four types of computer credibility described in Chapter 6—presumed, reputed, surface, and earned—also apply to users’ experiences on the Web. Table 7.6 reviews each type of credibility and lists a Web-related example for each.

Table 7.6: The Four Types of Web Credibility





Type of credibility

Based on general assumptions in the user’s mind

Based on third-party endorsements, reports, or referral

Based on simple inspection, first impressions

Based on first-hand experience that extends over time

Web example

A domain name that ends with “.org”

A site that won an award from PC Magazine

A site that looks professionally designed

A site that has consistently provided accurate information over the past year

Presumed Credibility on the Web

Presumed credibility describes the extent to which a person believes something because of general assumptions. These assumptions help people evaluate—rightly or wrongly—the credibility of Web sites.

Many elements from the Stanford Web Credibility Studies relate to presumed credibility. The four key elements that boost presumed credibility are shown in Table 7.7. (Our studies had no items that decreased presumed credibility to any practically significant extent.) First, the results show that sites are seen as more credible if they “represent a nonprofit organization” or have a URL that ends with “.org,” which many people associate with nonprofit organizations. [31 ]

Table 7.7: Key Elements That Increase Presumed Web Credibility



The site represents a nonprofit organization.



The URL for the site ends with “.org.”



The site provides links to its competitors’ sites.



The site says it is the official site for a specific topic.



Many people assume that, because nonprofit organizations are not seeking commercial gain, they are more likely to be trustworthy. This assumption is not always based in fact, but it does have an effect when it comes to perceived Web credibility.

Why the significant difference in scores for these two elements between 1999 and 2002? Clearly, nonprofits have lost some of their luster on the Web. The reason may have to do with people realizing that most anyone can set up a site that appears to be a nonprofit organization. As people gain more experience with the Web, they also are developing a healthy skepticism—things are not always what they appear to be, even with nonprofits. (Despite this decline in scores, it’s important to note that Web sites for nonprofits and those ending with “.org” still are evaluated positively in regard to credibility.)

Another key finding: A site is more credible if it “links to its competitors’ sites.” The likely assumption behind this finding is that companies that give users all the facts, including those not under their control, are being totally honest. By helping people access information—even information that may not be in the source’s best interest—the source will be viewed as highly trustworthy. [32 ]

The last key element that contributes to presumed credibility is having a site that “says it is the official site for a specific topic.” [33 ]The assumption is that official sites have more expertise on a given topic than a site that isn’t official.

Official sites also may be assumed to be more trustworthy because if they were not fair or honest, they would lose their official status. (Of course, Web users still need to determine if the site that declares itself to be the “official” site is telling the truth.)

Reputed Credibility on the Web

People’s perceptions of Web credibility often center on reputed credibility, a form of credibility that’s based on the endorsement or recommendation of a third party. On the Web, reputed credibility shows up in the form of awards, seals of approval, links, and endorsements from friends, among others. The key elements that affect reputed credibility are shown in Table 7.8. (As with presumed credibility, no item in our studies decreased reputed credibility to any practically significant extent.)

Table 7.8: Key Elements That Increase Reputed Web Credibility



The site displays an award it has won.



The site is linked to by a site you think is believable.



The site was recommended to you by a friend




The Web has spawned many endorsements in the form of awards (Figure 7.5). Some sites prominently list the awards they have won—site of the day, a top Web site, teacher approved. Posting awards is a good strategy to play up reputed credibility. Our study results show that they are a key element in enhancing perceptions of Web credibility, but perhaps not as much as we expected. It may be that the people in our sample were experienced enough to know that some awards on the Web are meaningless. This explanation seems especially true when you look at the change from 1999 to 2002. In 2002, participants reported that having received an award boosts perceived credibility of a Web site very little, if at all. Research in future years will help show if this decline was a fleeting result or something more permanent.

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Figure 7.5: Awards posted on Web sites can boost credibility, even though some people recognize that Web awards can be “pointless.”

Seals of Approval

Seals of approval (Figure 7.6) are similar to awards. A handful of companies have set out to tame the lawless World Wide Web—or at least to offer users a sense of security. The lack of regulation on the Web has created a market for third-party endorsements. Similar to UL Lab endorsements or Good Housekeeping seals of approval, Web-related endorsements can convey credibility.

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Figure 7.6: Various organizations have leveraged the fact that users seek third party endorsements on the Web.

Consider TRUSTe, a nonprofit consumer advocacy group. The trademarked motto for TRUSTe cuts to the heart of credibility: “Building a Web you can believe in.” VeriSign—“the sign of trust on the net”—also aims to give a sense of security to people who make Web transactions. In the health arena, the Health on the Net Foundation has created a set of guidelines for health sites. Sites that display the HON code logo are supposed to follow the policies of the foundation.

Organizations such as TRUSTe, VeriSign, and the Health on the Net Foundation have found they can fill a void. Consumer Reports is currently moving into this space with its Consumer Web watch Project, for which I serve as an adviser. [34 ]Web site operators seek these third-party endorsements, and Web users rely on them to determine the trustworthiness of Web sites.

Links from Credible Sources

Links from other Web sites to a given site also can convey credibility. The results from our studies confirm the impact of these incoming links. The studies showed that Web sites gain a great deal of credibility when “linked to by a site you think is believable.” This effect is intuitive: If you were running a Web site on health information, a single link from a prestigious site such as the Mayo Clinic could dramatically boost your site’s credibility. Through the link from their site, you received an implied endorsement from a prestigious organization.

Word-of-Mouth Referrals

Finally, our study data show that the classic word-of-mouth strategy boosts perceptions of Web credibility. Sites that are “recommended to you by a friend” are perceived as more credible. This is not surprising; in general, you would expect your friends to be trustworthy, looking out for your best interest.

The power of word-of-mouth referrals is not new, but it can take on new forms online. Some Web sites make it easy for you to send an article to a friend. Other sites, such as the community site Yahoo Groups, ask you to compose a personal message to a friend when you invite him or her into your virtual group. These are all referrals, which boost perceptions of site credibility.

The Web offers other types of reputed credibility, such as experts who endorse a site, magazines that favorably review a site’s functionality or content, and search engines that list the site early in the list of matches. Although not part of our studies, these all likely have an impact on the perceived credibility of Web sites.

Surface Credibility on the Web

Presumed and reputed credibility can exist without people experiencing Web sites firsthand; however, the other types of credibility—surface and earned— require direct experience. Of the two, surface credibility is the most common, while earned credibility is the most robust.

Often people use the Web in ways that don’t allow for earned credibility to develop. They surf around, hopping from page to page and site to site, making quick evaluations of Web credibility by browsing through sites. For casual Web surfing, surface credibility matters most and earned credibility matters little, since people are not processing information deeply and are not engaging with a site over an extended period of time.

Design Matters

What conveys the surface experience of a Web site, and how does this affect perceptions of credibility? Tables 7.9 and 7.10 show the key elements.

Table 7.9: Key Elements That Increase Surface Web Credibility



The site looks professionally designed.



The site has been updated since your last visit.



Table 7.10: Key Elements That Decrease Surface Web Credibility

1999 `


The site makes it hard to distinguish ads from content.



The site automatically pops up new windows with ads.



The site takes a long time to download.



The site requires a paid subscription to gain access.



The site has one or more ads on each page.



One key element in surface credibility is visual design. People can quickly take in the design of a site—the colors, the layout, the images, and other design elements. The Stanford Web Credibility Studies show that site design matters a great deal in assessing surface credibility. Sites that look “professionally designed” boost credibility substantially. People apparently use these limited impressions to make an initial assessment of a site’s credibility.

When evaluating credibility, Web surfers also consider how easy a site is to access. Sites that require “a long time to download” take a credibility hit. Also, according to the data in our studies, sites that require “a paid subscription to gain access” lose some credibility. [35 ]

Advertising is another element that affects surface credibility perceptions. People surfing the Web may not read a Web site’s content in detail, but they are likely to get a sense of the advertising on the site. As noted earlier, a site loses a great deal of credibility by making it “hard to distinguish ads from content” or by “automatically pop[ping] up new windows with ads.” As stated earlier, popup ads are more common in 2002 and, therefore, more annoying. It only takes a quick glance to sense the ad density on a page, making this a surface credibility issue. Participants in our research studies reported that sites having “one or more ads on each page” lose credibility.

Enhancing Surface Credibility

Because people can’t absorb all Web site elements at once, Web designers must emphasize those elements that boost surface credibility most. Which elements to emphasize depends on the Web site’s purpose. For example, if a site deals with news, it’s important to quickly show that the site’s information is current. Our studies show that sites gain credibility when they have been “updated since your last visit.” To boost surface credibility, a news Web site could highlight the frequency of its updates.

Another example: If a site deals with health, it’s important to convey the expert sources behind the information. In a recent pilot study asking people to compare the credibility of health Web sites, researchers in my Stanford lab found that participants responded quite positively to (Figure 7.7). In reading their comments, we found that one element made InteliHealth seem highly credible: the use of the Harvard Medical School name. Every page of the InteliHealth site contains in the upper left corner a prominent blue oval that says “Featuring Harvard Medical School’s Consumer Health Information” along with an image of the Harvard crest. This is great example of bringing to the surface elements that are likely to boost credibility. The designers at InteliHealth did not hide the Harvard affiliation in a footnote or an “about us” page; the message is featured on each page, taking up valuable screen space but doing an important thing for a health site: clearly establishing credibility.

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Figure 7.7: By making the Harvard name prominent, InteliHealth gains surface credibility.

Designing for surface credibility is a balancing act. On the one hand, a site must fill users’ needs for information or services quickly—or at least make a quick promise to fill those needs. A portion of the homepage must be devoted to this. On the other hand, the site must use the homepage to convey surface credibility—by showing a photo of the organization’s headquarters building; listing clients, partners, or experts associated with the site; or including other content that instantly conveys expertise or trustworthiness. Both of these requirements must be met within the limitations of a browser window.

Earned Credibility on the Web

The last type of Web credibility is the gold standard: earned credibility. Especially on the Web, where people surf quickly from site to site, earned credibility is the most difficult type to gain, but it is also the type of credibility that is most likely to lead to attitude and behavior changes. Conveying the three other types ofWeb credibility is useful primarily so that the site will eventually gain earned credibility. When earned credibility is high, people are likely to spend more time at the site, visit it more often, make repeated purchases (if it is an e-commerce site), tell others about it, and be open to persuasion techniques the site uses. Earned credibility is all about establishing an ongoing relationship between a Web user and the Web site or operator. According to our research, a solid, ongoing Web relationship is based on three key attributes of a site: interactions are easy, the site’s information is personalized, and service is responsive (Tables 7.11 and 7.12).

Earned credibility is the most difficult to achieve but the most likely to change attitudes or behaviors.

Table 7.11: Key Elements That Increase Earned Web Credibility



The site sends emails confirming transactions you make.



The site is arranged in a way that makes sense to you.



The site recognizes you have been there before.



The site selects news stories according to your preferences.



The site has ads that match the topic you are reading about.



The site provides a quick response to your customer service questions.



Table 7.12: Key Element that Decreases Earned Web Credibility



The site is difficult to navigate.



The Interaction Is Easy

Earned credibility grows from Web interactions that are easy. Our survey results show that Web sites gain credibility when “the site is arranged in a way that makes sense to you.” At the opposite end of the spectrum, a site loses credibility when it “is difficult to navigate.”

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Principle of Ease-of-Use

A Web site wins credibility points by being easy to use.

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Likability is a stepping stone to credibility. A person who likes someone tends to think the other person is credible as well. [36 ]The same is true for human-computer relationships. [37 ]If a person finds a Web site easy to use, he or she likely will think the site is also credible.

The Information Is Personalized

In our studies, we found that a Web site was perceived to be more credible when it offers personalized information—specifically, when it “recognizes you have been there” and when it selects “news stories according to your preferences.” Even ads on the Web become slight bonuses when they are personalized; the study data show that a site gains credibility when the “ads match the topic you are reading about.”

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Principle of Personalization

Web sites that offer personalized content and services get a boost in credibility.

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Personalization seems to enhance credibility in two ways. First, when a Web site has the capability to tailor content, people will view the site as smarter, boosting expertise perceptions. Next, tailored experiences can make people think the Web site understands their preferences and is working to help them achieve their goals. Unless the tailoring is done poorly (e.g., raising concerns about privacy by clumsily showing how much the Web site really knows about you38), users are likely to perceive the site—and the people behind it—as trustworthy. For instance, people who use sites such as or may view the personalized versions of these Web sites as more trustworthy.

The Service Is Responsive to Customer Issues

Finally, Web sites can earn credibility when people find them responsive. Our studies show significant increases in credibility for a Web site that “provides a quick response to your customer service questions.” Participants also evaluated a Web site to be much more credible when it “sends emails confirming transactions you make.” It may be that, in the period between the 1999 study and the 2002 study, people had become more comfortable with online transactions and that the email confirmation was less needed—or more expected.

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Principle of Responsiveness

The more responsive to users, the greater the perceived credibility of a Web site.

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Earned credibility should be a key goal for creators of persuasive Web sites. The study data highlight some specific design issues for achieving this: make Web sites easy to use, personalized, and responsive. These three factors will do more than perhaps anything else to boost credibility perceptions that make a difference.

[31 ]When this study is complete, the results will be posted online at

[32 ]In 1999, I advised a Stanford honors thesis investigating Web credibility. The results from this controlled laboratory study also showed that simple typos have clear negative effects on Web credibility. The more important the information (e.g., life-depending information), the stronger the negative effect. Thesis information: N. Kim, World Wide Web Credibility: What Effect Do Advertisements and Typos Have on the Perceived Credibility of Web Page Information? Senior honors thesis, Stanford University (1999).

[33 ]In recent years hackers have brought down Web sites for titans like Yahoo, the New York Times, and eBay. This can be costly, in terms of lost dollars and lost credibility. For example, when eBaywent down for 22 hours in 1999, not only did it cost the company $3.9 million in credits given to users and a 9% drop in share price, media reports suggested that the downtime also cost eBay credibility among its users. See the following:

[34 ]You don’t need to be a nonprofit organization to register a domain name with an “.org” ending. Anyone can purchase these domain names, but many people don’t know this.

[35 ]E. Walster, E. Aronson, and D. Abrahams, On increasing the persuasiveness of a low prestige communicator, Journal of Experimental Social Psychology, 2: 325–342 (1966).

See also S. Chaiken and D. Maheswaran, Heuristic processing can bias systematic processing: Effects of source credibility, argument ambiguity, and task importance on attitude judgment, Journal of Personality and Social Psychology, 66: 460–473 (1994).

[36 ]We deleted this topic in the 2002 survey because we felt it applied to a small number of sites.

[37 ]See