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    Path to Science

    Thinking Dictionary

    Credible sources

    What it is

    A credible source is one you have good reason to trust on the question in front of you. Three questions do most of the work:

    • Expertise. Does this person or organisation have real training or experience in this topic?
    • Track record. Have they been right before?
    • Stake. Do they gain something if you believe one particular answer? This is called a conflict of interest.

    Credibility depends on the topic. A brilliant heart doctor is not automatically an expert on the climate.

    Why it matters

    Nobody can check everything themselves. For most technical questions, the realistic skill is not doing all the research yourself. It is judging whom to trust.

    The trouble is that we are not naturally good at this. Studies going back to the 1950s show that how believable a source seems affects how much it persuades us.¹˒² A review of five decades of this research found the effect generally holds, though it varies with the situation.² But seeming credible is about persuasion, not truth. A confident voice and a polished website are cheap.

    In everyday life

    • Who paid for the study? A systematic review gathers and assesses all the studies on a question. One such review looked at research on medicines and medical devices. Studies paid for by the companies that make them more often reported favourable results, and more often drew favourable conclusions, than other studies. Yet on standard checks for bias, the company-funded studies didn't look worse. That suggests the effect is subtler, such as which questions get asked and how results are framed.³ This doesn't mean company-funded research is false. It means it is worth looking for independent confirmation.
    • A website that looks official. In one study, professional fact-checkers judged websites better than historians and university students did. The fact-checkers quickly left the website and looked up what others said about it. The others mostly stayed on the page and read it closely.⁴ Checking a source by opening other tabs like this is called lateral reading, and it has its own entry. Students in particular often struggle to judge online sources.⁵
    • "It was published in a scientific journal." Before a study is published, other experts usually review it. This is called peer review. It helps, but it doesn't guarantee a result is right. When researchers tried to repeat 100 published psychology studies, many of the results didn't come out the same way again.⁶
    • A celebrity's health tip. Ask the three questions. What is their training in health? Have they been right before? Do they sell a product connected to the tip?

    The common trap

    The first trap is judging credibility by surface signs: confidence, a good-looking website, or a title.

    The second trap goes too far the other way: assuming any conflict of interest means someone is lying. A stake in the answer is a reason for extra checking, not a reason to throw everything out.³

    A third trap is "I'll just do my own research." For most technical questions, the better question is which experts to rely on.

    Some ways out:

    • Ask the three questions: expertise, track record, stake.
    • Leave the page and see what others say about the source.⁴
    • Look for independent experts who reach the same conclusion.

    Try it

    Pick a health claim you saw this week. Give yourself five minutes and answer these questions:

    1. Who is behind the claim?
    2. What training do they have in this topic?
    3. Have they been right before? Search their name with "correction" or "fact check."
    4. What do they gain if you believe it?

    Then find one independent expert body, such as a national health agency, and see what it says about the same claim. Do they agree?

    Related concepts

    Lateral reading · Confirmation bias · Multiple lines of evidence · Iteration · Correlation vs causation · Peer review · Misinformation vs disinformation

    Sources

    1. Hovland, C. I., & Weiss, W. (1951). The influence of source credibility on communication effectiveness. Public Opinion Quarterly, 15(4), 635–650. https://doi.org/10.1086/266350

    2. Pornpitakpan, C. (2004). The persuasiveness of source credibility: A critical review of five decades' evidence. Journal of Applied Social Psychology, 34(2), 243–281. https://doi.org/10.1111/j.1559-1816.2004.tb02547.x

    3. Lundh, A., Lexchin, J., Mintzes, B., Schroll, J. B., & Bero, L. (2017). Industry sponsorship and research outcome. Cochrane Database of Systematic Reviews, 2017(2), MR000033. https://doi.org/10.1002/14651858.MR000033.pub3

    4. Wineburg, S., & McGrew, S. (2019). Lateral reading and the nature of expertise: Reading less and learning more when evaluating digital information. Teachers College Record, 121(11), 1–40. https://doi.org/10.1177/016146811912101102

    5. McGrew, S., Breakstone, J., Ortega, T., Smith, M., & Wineburg, S. (2018). Can students evaluate online sources? Learning from assessments of civic online reasoning. Theory & Research in Social Education, 46(2), 165–193. https://doi.org/10.1080/00933104.2017.1416320

    6. Open Science Collaboration. (2015). Estimating the reproducibility of psychological science. Science, 349(6251), aac4716. https://doi.org/10.1126/science.aac4716