What criteria determined if an intervention was effective?
The NPDC determined if an intervention was effective through a review of peer-reviewed research in scientific journals.
An intervention was considered to be an evidence-based practice if it met the specific criteria outlined below.
randomized or quasi-experimental design studies. Two high quality experimental or quasi-experimental group design studies conducted by at least two different researchers or research groups, OR
single-subject design studies. Five high quality single subject design studies conducted by three different investigators or research groups and having a total of at least 20 participants across studies, OR
combination of evidence. One high quality randomized or quasi-experimental group design study and at least three high quality single subject design studies conducted by at least three different investigators or research groups (across the group and single subject design studies).