Can increasing surface credibility improve e-health intervention effectiveness?

  • Thomas Nind

    Student thesis: Doctoral ThesisDoctor of Philosophy


    One way internet users determine the quality of a website is to look for so called 'credibility factors'. These factors can either be positive: the presence of a date, reference list, independent site certification; or negative: the presence of advertisements or broken links.
    This thesis investigates what role such factors play in the effectiveness of two e-health interventions. An e-health intervention is a health related website designed to change a person’s behaviour.
    Until now research into credibility has been largely theoretical. Studies have relied on subjective outcome measures such as Likert scales, website content recall, expressions of preference and self reported behaviour. This thesis describes two studies, the second of which investigates, for the first time, whether surface credibility manipulations change objective behavioural outcomes. Surface credibility is how much a perceiver believes a website on simple inspection. Based on a comprehensive literature review of credibility
    research, the following credibility factors were explored: presence of advertising, recognisable logos, contact details, physical address, references, third party certification, currency information, privacy statement, HTTPS encryption, top level domain and presence of a broken link.
    The first study involved the assembly of an exercise promotion website. Participants were randomised to receive the site modified to contain either factors heightening credibility or those lowering credibility. Participants using the high credibility version spent twice as long browsing the site as those using the low credibility version. There was no effect on attitude
    to exercise or self reported physical activity.
    The second study used the same methodology but with a website targeting an objectively measurable health behaviour (registration as an organ donor). In this study 889 university students were exposed to a website promoting organ donation. Information on the site was assembled based on theoretical domain interviewing and current research into organ donation interventions. 336 (37.79%) participants registered through the study website. The study
    detected no significant difference in registration rates between high and low credibility versions of the site. Of the 17 comments left on the low credibility site, only 3 were credibility related criticisms.
    It is the finding of this thesis that university students are willing to submit personal information and place trust in a website contravening many current credibility guidelines. Future studies into credibility are needed to explore why this is the case. One possibility is that the website was trusted simply because it was part of a research study. Another possibility is that the high quality of the textual content compensated for the lack of
    credibility of the site itself.
    It is the recommendation of this thesis that future studies focus on objective behavioural outcome measures and control for other forms of credibility such as participation in a research study.
    Date of Award2012
    Original languageEnglish
    SupervisorIan Ricketts (Supervisor)


    • Credibility
    • HCI
    • Quality assessment
    • Trust
    • Believability
    • E-health
    • Intervention
    • Organ donation

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