Let’s start at the top of the pyramid, with RCTs, or Randomized controlled trials.
Randomized controlled trials (RCTs) are generally thought of as the “gold standard” when researchers are comparing interventions. In RCTs, participants of similar characteristics are randomly placed in either an intervention or a control group. The study then evaluates and compares the outcomes between the two groups.
When to include: In most cases, if RCTs exist for your question, you’ll want to use them in your systematic review. They’re especially useful for questions comparing the effectiveness of different treatment approaches. If the study includes follow up with participants, it can also help you examine questions related to safety.
On the next page, we’ll move down to cohort studies.