Estimand
Definition
A precise statement of what a trial is estimating: the population, the endpoint, and how events such as discontinuation are handled. Two analyses of one dataset can differ because they answer different estimands rather than because one is wrong.
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
Adherence
The extent to which participants followed the assigned protocol. Low adherence pulls a result toward no difference, so it is reported alongside the outcome rather than treated as a footnote.
Experimental Model
The system a finding was produced in: a cell line, an isolated tissue, an animal strain, or human participants. It bounds what the finding supports, and the gap between a cultured cell and an organism is where most translation failures occur.
Clinical Trial
A study testing an intervention in human volunteers under a protocol fixed before enrolment. The protocol, not the published paper, is what defines the question the trial was built to answer.
Randomized Controlled Trial (RCT)
A study in which participants are allocated to arms by chance, so that known and unknown differences between groups even out. It is the strongest single-study design for showing that an intervention caused an outcome.
Phase I Trial
First administration in humans, typically 20 to 100 volunteers, looking at safety, tolerability and pharmacokinetics rather than at whether the compound works. Most research peptides have never reached this stage.
Phase II Trial
Up to several hundred participants with the condition in question, testing whether there is an effect worth confirming and finding the amount to carry forward. It is where most candidates fail.
Phase III Trial
The pivotal study, commonly 300 to 3,000 participants or more, powered on a pre-specified endpoint and comparing against placebo or standard care. Approval decisions rest on it.
Phase IV Trial
Study after approval, in ordinary clinical use rather than in a selected trial population. Long-term and rare harms surface here, which is why an approval is not the end of the evidence.