Answered By: Rachel Lerner
Last Updated: Aug 04, 2021     Views: 64

  • CLINICAL TRIALS For the purposes of registration, a clinical trial is any research study that prospectively assigns human participants or groups of humans to one or more health-related interventions to evaluate the effects on health outcomes.  Source:
  • CONTROLLED CLINICAL TRIALS A clinical study that includes a comparison (control) group. The comparison group receives a placebo, another treatment, or no treatment at all. Source:
  • RANDOMIZED CONTROLLED TRIALS Randomized controlled clinical trials are carefully planned experiments that introduce a treatment or exposure to study its effect on real patients. They include methodologies that reduce the potential for bias (randomization and blinding) and that allow for comparison between intervention groups and control (no intervention) groups. A randomized controlled trial is a planned experiment and can provide sound evidence of cause and effect. Source:​
    • PHASE I CLINICAL TRIAL The first step in testing a new treatment in humans. A phase I study tests the safety, side effects, best dose, and timing of a new treatment. It may also test the best way to give a new treatment (for example, by mouth, infusion into a vein, or injection) and how the treatment affects the body. The dose is usually increased a little at a time in order to find the highest dose that does not cause harmful side effects. Phase I clinical trials usually include only a small number of patients who have not been helped by other treatments. Sometimes they include healthy volunteers. Source:
    • PHASE II CLINICAL TRIAL A study that tests whether a new treatment works for a certain type of cancer or other disease (for example, whether it shrinks a tumor or improves blood test results). Phase II clinical trials may also provide more information about the safety of the new treatment and how the treatment affects the body. Source:
    • PHASE III CLINICAL TRIAL A study that tests the safety and how well a new treatment works compared with a standard treatment. For example, phase III clinical trials may compare which group of patients has better survival rates or fewer side effects. In most cases, treatments move into phase III trials only after they meet the goals of phase I and II trials. Phase III clinical trials may include hundreds of people. Source:
    • PHASE IV CLINICAL TRIAL A type of clinical trial that studies the side effects caused over time by a new treatment after it has been approved and is on the market. These trials look for side effects that were not seen in earlier trials and may also study how well a new treatment works over a long period of time. Phase IV clinical trials may include thousands of people. Also called post-marketing surveillance trial. Source:


To learn more about types of studies, visit our Resource Evaluation Research Guide



Submit a Question

Your email is safe with us - we will not share it, but we need it to answer you!
Your Question
Your Info
Fields marked with * are required.