Evidence Ratings

• Scientifically Supported: Strategies with this rating are most likely to make a difference. These strategies have been tested in many robust studies with consistently positive results.

• Some Evidence: Strategies with this rating are likely to work, but further research is needed to confirm effects. These strategies have been tested more than once and results trend positive overall.

• Expert Opinion: Strategies with this rating are recommended by credible, impartial experts but have limited research documenting effects; further research, often with stronger designs, is needed to confirm effects.

• Insufficient Evidence: Strategies with this rating have limited research documenting effects. These strategies need further research, often with stronger designs, to confirm effects.

• Mixed Evidence: Strategies with this rating have been tested more than once and results are inconsistent or trend negative; further research is needed to confirm effects.

• Evidence of Ineffectiveness: Strategies with this rating are not good investments. These strategies have been tested in many robust studies with consistently negative and sometimes harmful results.   Learn more about our methods