How to read scientific studies
A paper is an argument supported by methods and data. Read beyond the headline and abstract to see whether the methods answer the question and whether the conclusion matches the results.
1. Identify the research question
Write the question in plain language. Identify the population, exposure or intervention, comparison and outcome. A clear question makes it easier to decide whether the chosen design is suitable.
- What exactly is being tested or estimated?
- What is the primary outcome?
- Was the question specified before the results were known?
2. Identify the study design
Randomised controlled trial
Participants are allocated by chance to comparison groups. Randomisation aims to reduce systematic differences between groups, although conduct, missing data and reporting can still introduce bias.
Cohort study
Groups are followed or reconstructed according to an exposure. Cohort studies can examine associations and rates but may be affected by confounding and selection.
Case-control study
People with an outcome are compared with people without it to examine previous exposures. Selection of controls and accurate exposure measurement are important.
Cross-sectional study
Exposure and outcome are measured around the same time. It can describe prevalence and associations, but the time order may be unclear.
Systematic review and meta-analysis
A systematic review uses pre-specified methods to find and assess relevant studies. A meta-analysis statistically combines compatible results. Its reliability depends on the search, included evidence, risk-of-bias assessment and suitability of the synthesis.
3. Read the methods before the conclusion
- Selection: how were participants recruited and who was excluded?
- Comparison: was there an appropriate control or comparison group?
- Measurement: were exposure and outcomes defined and measured consistently?
- Bias safeguards: were randomisation, allocation concealment or blinding used where appropriate?
- Confounding: which alternative explanations were measured and adjusted for?
- Follow-up: how much data were missing and did loss differ between groups?
- Protocol: do the reported outcomes match those planned or registered?
4. Read the results in absolute as well as relative terms
Find the number of participants and events in each group. Relative measures can make a difference appear large when the absolute difference is small, while absolute figures alone may obscure proportional differences. Both can be useful when presented with the underlying time period and population.
5. Separate statistical significance from importance
A p-value addresses a statistical question under a model; it does not measure the probability that the claim is true, the size of an effect, its practical importance or the absence of bias. Read it alongside the effect size, confidence interval, absolute numbers and study limitations.
6. Check whether the conclusion overreaches
- Does observational evidence use causal language without sufficient support?
- Does the conclusion apply beyond the population or follow-up studied?
- Are secondary or subgroup findings presented as if they were the main result?
- Does the abstract omit important uncertainty or adverse outcomes?
- Are limitations acknowledged and reflected in the wording?
7. Put one study into the wider evidence base
Compare the paper with other relevant studies, systematic reviews, regulatory assessments and guidance. Differences may reflect populations, interventions, outcomes, study quality or chance. A new paper can add information without overturning the wider evidence by itself.
8. Check funding and conflicts without using them as shortcuts
Read funding and conflict-of-interest declarations and consider how study design, analysis or reporting might be affected. A disclosed interest does not automatically invalidate a study, and absence of a declared interest does not establish that the methods are sound. Judge the evidence and its safeguards directly.
Methodology sources
Cochrane Handbook — bias and conflicts of interest
Cochrane Handbook — assessing risk of bias in randomised trials
Educational scope
This guide provides general research-literacy information. It does not independently appraise every study and does not replace personal medical advice from a suitably qualified healthcare professional.