Case Report and Case Series
Definition
A published description of one patient, or a handful, with no control group. Useful for flagging a rare harm or an unexpected observation, and not evidence that something works.
What this means for research sourcing
Understanding evidence quality helps researchers prioritize compounds. Volta's research library summarizes the literature behind stocked compounds.
Related Terms in Evidence & Research
Observational Study
Research that records what happens without assigning the intervention, in cohort or case-control form. It shows association at a scale trials cannot reach and can never rule out that the groups differed to begin with.
Systematic Review
A review that follows a search and appraisal protocol written in advance, so which studies were included is reproducible rather than left to the author's discretion.
Meta-Analysis
Statistical pooling of results from several studies into one estimate. Its reliability is capped by the quality of what it pools and by which studies were published in the first place, so a pooled figure is not automatically a better one.
Cochrane Review
A systematic review published by Cochrane, an international network with published methodology and conflict-of-interest rules. Cochrane reviews are generally treated as among the more rigorous syntheses available.
Publication Bias
The tendency for positive results to be published while null and negative ones are not, which leaves the visible literature skewed toward effects. In a field with few large trials it is the single largest distortion.
Peer Review
Assessment of a manuscript by independent researchers before a journal publishes it. It catches some errors and does not verify that the underlying data exist or are correct.
Retraction
A journal's formal withdrawal of a published paper for error or misconduct. Retracted papers keep accruing citations for years, so a claim can stay in circulation long after its source was withdrawn.
Expression of Concern
A notice a journal attaches to a paper when it has credible doubts about its integrity but has not finished investigating. It is a warning short of retraction and is easy to miss on a citation.