Distinguishing reliable sources for public health

A primary source

This is a first-hand account of new information, such as: a dataset created by taking measurements or recording observations; an academic paper which details an experiment which has been conducted and its results. Journalistic accounts of events witnessed first-hand are often considered primary sources, although these are less trustworthy than empirical data, and may contain exaggeration, spin, or errors. 

A secondary source 

This is one step removed from a primary source. They generally quote or reference primary sources, but add another layer of interpretation, analysis, or generalisation. They include textbooks, news media reporting on a primary source which has been published elsewhere, an academic paper that reviews or analyses the findings of other papers, not having conducted experiments directly itself. 

A tertiary source 

Definitions of tertiary resources differ, generally these are a step further removed from secondary resources. This could include an opinion piece which only references secondary resources, with no indication the author has read the primary material. It could be a Facebook post in which a third party summarises their interpretation of the points in a secondary source.

Primary sources are generally reliable sources of basic facts and fine detail. Their ‘background’ sections generally provide clear, more generalised overviews which are useful to people not familiar with the subject, with links to other primary resources. 

Secondary sources are often written for non-experts and focus more on the implications of new data. This can make them more useful for non-experts, but the inferences they make have the potential to contain opinion, assumptions, and inaccuracies. It is important to read secondary sources with a critical eye, as laid out in the rest of this article. 

Tertiary sources, where a third party presents their views on a secondary source, are particularly likely to be unreliable. Inaccurate articles are more likely to be shared on Facebook than accurate articles.^[3] 

Think about how frequently you have been hearing updates about the topic of interest. If new information is emerging every few months and the source is a year old, be aware that some information it contains may no longer be correct.

In the first months of the pandemic, we went from knowing nothing about the virus, to having some ideas about how it worked, to realising those were wrong and having different theories, within weeks.

Reading dense academic sources from fields you aren’t familiar with can lead to you misinterpreting otherwise accurate information. If you’re struggling to follow the basic narrative and reasoning in the abstract, background, or conclusion of an article, it might be better to find a secondary resource that explains the article in lay terms. 

Content which has been published by a company with a vested interest in the narrative it communicates is not necessarily unreliable. Companies which have developed products are often the only people who are able to validate their work and publish results early on. However, in these cases, it is worthwhile looking at the results more closely than if they were published by an independent source, and look for corroborating independent sources or commentary by independent experts. Academic journal articles are required to declare any conflicts of interest authors of their articles may have, generally listed at the end of the article.

The best sources are those written by subject matter experts, who don’t have a political or financial incentive to misrepresent the facts. Sites ending in .edu or .gov or .gov.[country] are therefore generally considered to hold reliable information (although all sources are faillible). The veracity of mainstream media sources is very variable, with some sources employing well-educated people to write well-researched, neutral content, and others doing the opposite. 

Various media bias and fact-checking websites exist (search those words to find them) which can help you understand the general reputation of a site when you are reading articles, and any biases they typically exhibit. 

Academic journals are generally good sources of reliable scientific information, because they tend to use rigorous quality control processes, including peer review by a group of experts. There are exceptions: sometimes a poor quality or misleading article will slip through peer review. Some sites publish articles before they have been reviewed (this will be clearly stated), meaning those articles need to be considered less credible for that time. There are a small number of journals which do no quality control and just publish articles for a fee. 

• If something still makes you feel sceptical of an article’s claims, look at recent papers which cite it, or secondary sources commenting on the findings to see how it has been received by experts in the field.

Sites or browsers which store your data sometimes try to tailor the results to your existing interests or beliefs, which can exacerbate any conscious or unconscious biases which have come up in your previous searches. Consider using web browsers or search engines which don’t track your search history while doing research.

Lack of credible references: articles which make statements which are presented as facts, rather than opinions, should provide links to the primary sources that support the statement. Articles which don’t cite sources, or cite tertiary rather than primary sources should be treated with suspicion. 

Use of absolute words: articles which tell you that ‘all research points to…’, ‘everyone knows that…’ ‘no one has ever…’ are generally not true – there’s always someone who disagrees, or an exception to a trend in research. Similarly, phrases such as ‘scientists say’, or ‘research shows’, should be followed by links to the sources that support the argument. ‘Thought terminating’ cliches such as ‘we’ll never know’, or ‘discussing it is pointless’ could also be grouped here, these are often found in social media discussions which contain misinformation.  

Loaded language: the use of emotive words, for example ‘monstrous’, ‘disgusting’, ‘shocking’, ‘terrifying’, ‘bravely’, ‘beautifully’ often indicates an article is trying to make you feel a certain way about the information it conveys, instead of leaving you to make your own judgement. An article which is written to deliver factual information in a neutral manner will avoid these words. It has also been found that articles using negative and loaded words spread faster, and misleading articles therefore tend to use more of these.^[4] 

Numerous spelling and grammar mistakes: indicate an article hasn’t been proof-read. If the subject matter is a first-hand account of someone’s personal experience, then that doesn’t matter. However, if the article is conveying scientific information or expert opinions, it is unlikely that a legitimate source would not have edited the copy.  

Ad-Hominem Attacks: articles focussed on attacking a person making an argument, rather than the points that they present. These are usually made by people who disagree with the views of their target, but can’t provide good evidence that those views are wrong.

False Dichotomies: arguments which present only a limited number of choices or sides of an argument as mutually exclusive of one-another, when this doesn’t represent the entire range of possibilities that exist around a subject. For example: “if you have a dog, that means you hate cats”. These arguments are misleading, and generally divert discourse away from real issues onto other manufactured conflicts.

Scopus - provides journal ranking metrics to help you identify those which will provide the most reliable information in a given field.

The Conversation - provides opinion and analysis written by academic experts.

Reuters - a news agency which adheres to ‘Trust Principles’ stipulating its journalists maintain freedom from bias. 

The Centres for Disease Control and Prevention - a US source of legitimate, evidence-based scientific information, generally written in plain English for a lay audience. 

The British Medical Journal - a British peer-reviewed medical journal. 

The Lancet - a leading global health journal trusted internationally as a source of health knowledge. 

Nature - a highly respected journal publishing peer reviewed research into natural sciences. 

The World Health Organisation - is a specialised agency of the United Nations with the objective to attain the highest possible level of health for everyone. 

Truth Labs for Education - is a collaborative project between Cambridge University, University of Bristol, and Google Jigsaw which creates short videos to help people identify online content that is designed to manipulate them. The videos are available on YouTube and on the Truth Labs website.