Misinformation relies on people not questioning the trustworthiness of the information. We can lower our susceptibility to misinformation by questioning its credibility, and enhancing our ability to discern between credible and false information. 

Imagine you come across a social media post claiming that a new supplement can cure illness. The post has thousands of shares and glowing testimonials, including celebrity endorsements. It would be easy to buy into and accept the claims at face value. Instead, you apply a critical approach: you check the source, look for supporting evidence from experts and reputable institutions, and consider whether the claim aligns with scientific consensus. You also reflect on your own biases - were you drawn to this information because it reinforces your desire for a quick and easy solution? When we question the credibility of the claim rather than relying on our feelings or the post's popularity, we lower our susceptibility to misinformation, and therefore can make more informed decisions. 

Often our worldviews, existing beliefs and cognitive biases shape how we process information, and what we accept to be true. To be more critical about the information we’re consuming, we can pay attention to our expectations or assumptions, and consider whether we might be dismissing evidence simply because it challenges our beliefs, or goes against our expectations or desires. 

Here are some ways to assess the credibility of information:

1. Check the source of information 

Ask yourself: Who is the source of information? What are the person’s qualifications or accreditations? Reliable information is backed by experts, research, and multiple trustworthy sources. Are they citing research to back up their claims? 

2. Check the study 

Are the study findings generalisable and valid? 

Who were the participants? Are they human, or non-human species? Some studies use animal models, yet their findings are sometimes presented as if they apply directly to humans, which can be misleading. For example, if a supplement reduces tumors in rats, it does not mean it will have the same effect in humans. When the sample population isn’t clearly mentioned, it creates a false impression of generalisability. 

Additionally, the sample's participant characteristics can impact how broadly findings apply, such as whether studies conducted were exclusively on males, individuals from a specific geographic region, or those with a particular health status. These factors should be considered when evaluating the relevance of study results.

How large is the sample population? 

Was the sample size sufficient to detect a meaningful effect, or was it too small to draw reliable conclusions? Studies with small sample sizes are more prone to random variation, and lack the power to establish strong, generalisable findings. Larger, well-powered studies help ensure confidence in the study findings. 

Have the findings been replicated? 

Confidence increases when results are reproduced across multiple independent studies, using diverse populations and methodologies. Replication strengthens the credibility of research and helps distinguish real effects. 

3. Understanding the hierarchy of scientific evidence

Not all evidence is made equal. Strong scientific evidence is built on rigorous methods, peer review, and reproducibility, while weaker forms of evidence often rely on anecdotal experiences or subjective interpretation. Understanding the hierarchy of evidence helps us critically assess claims, avoid misinformation, and make informed decisions. While all types of research contribute to scientific knowledge, stronger evidence provides a more reliable foundation for guiding policy, healthcare, and public understanding. This article explores the different types of scientific evidence. 

What Is not scientific evidence?

• Personal stories and testimonials – individual experiences can be influenced by bias, placebo effects, or confounding factors.
• Gut feelings and iIntuition - whilst intuition can sometimes be useful in decision-making, it is not a reliable basis for factual claims. Scientific evidence requires measurable, observable, and repeatable results.

What Is scientific evidence?

See the hierarchy of evidence from strongest to weakest:

1. Meta-analyses and systematic reviews. This is the gold standard of scientific evidence and sits at the top of the hierarchy. Meta-analyses statistically combine data from multiple studies, reducing bias and increasing reliability. Advantages of a meta-analysis are improved confidence in findings, the opportunity to settle conflicting claims, and the ability to answer questions not investigated by single studies. Systematic reviews critically evaluate existing research to determine the current state of the research in that area. These provide the most reliable evidence by reducing bias and increasing sample size across studies.
2. Randomised controlled trials (RCTs). RCTs are considered the gold standard for experimental research, RCTs randomly assign participants to different conditions (e.g. a control and experimental condition) to test a cause-effect relationship. 
3. Cohort studies. These follow a group of people over time to assess associations between risk factors and outcomes, offering strong observational evidence but without the control of an RCT (e.g. control group). 
4. Case-control studies. These studies compare individuals with a specific outcome (e.g., a disease) to those without it to identify potential contributing factors. However, these studies cannot infer causality. 
5. Cross-sectional studies. These studies examine a population at a single point in time, providing a snapshot of associations. Cross-sectional studies cannot infer causality, only that a relationship exists. 
6. Animal trials and laboratory research. This type of research is valuable for early-stage scientific exploration. However, findings from animal models do not always translate directly to humans. 
7. Case reports and opinion papers. These types of papers provide insights or expert perspectives, but lack controlled study designs, making them the weakest form of scientific evidence.

Here is a checklist to help you critically assess the credibility of information:

• Is the information backed by experts, research, or multiple trustworthy sources?

• Are claims supported by cited research?

• Are the study findings generalisable and valid?

• Who were the participants? Human or non-human species?

• How large is the sample population?

• Have the findings been replicated in multiple independent studies?

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