Placebo
Definition
An inactive preparation made to look like the active one, given to the comparison arm. Placebo groups routinely improve, which is exactly why an uncontrolled result cannot be read as evidence of an effect.
Where this term comes up
Entries whose definition mentions Placebo.
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
Placebo-Controlled
A design in which the comparison arm receives placebo rather than nothing or another active agent, isolating the intervention's own contribution to whatever changed.
Placebo Effect
Improvement that follows the expectation of treatment rather than the treatment itself. It is real, measurable and occasionally large, and separating it from a drug effect is the entire purpose of a control arm.
Crossover Trial
A design in which each participant receives both treatments in sequence with a washout between, so each person acts as their own control. It needs fewer participants and only suits stable, reversible conditions.
Intention-to-Treat
Analysing every participant in the arm they were randomised to, whether or not they finished. It preserves the randomisation and usually gives a more conservative answer than analysing completers only.
Endpoint
A defined, measurable outcome a trial uses to judge an intervention. Which endpoints were chosen, and when, is as informative as the results reported against them.
Primary Endpoint
The single outcome a trial was designed and powered to answer, fixed before data collection. Secondary endpoints are informative and are not what the trial succeeded or failed on, a distinction that press releases regularly blur.
Biomarker
A measurable indicator standing in for a process, a disease state or a response. Serum IGF-1 is the usual biomarker in growth hormone secretagogue work, and a biomarker moving is not the same as an outcome improving.
HbA1c (Glycated Hemoglobin)
A blood measure reflecting average glucose over roughly the preceding two to three months, reported as a percentage. It is the standard primary endpoint in metabolic trials, which is why a result quoted in points of HbA1c appears in almost every incretin paper.