TABLE 1.

Phases (types) of clinical trials and examples of key activities in each clinical trial process.

Phase	Explanation
One	An exploratory investigation of safety and the effects of dosage in a small number of healthy participants.
Two	A preliminary estimate of efficacy (i.e., the potential of the intervention to provide benefit), in a small number of participants with the specific health condition.
Three	A definitive trial of effectiveness, involving a relatively large number of participants who are randomized to the intervention(s) or control.
Four	Monitors side effects and how well the intervention works over a longer period and in a very large number of participants.
Stage	Key activities
Pre-trial	• Formulate the PICO research question • Design trial
Trial set-up	• Protocol and ethics • Operating procedures, including case report forms for collecting de-identified data • Set-up site(s) • Register trial
The trial	• Collect and store data • Regularly review for protocol adherence
End of trial	• Lock database and undertake statistical analysis • Identify and deal with missing data • Disseminate trial findings