Our Ratings

Evidence Rating

“Evidence of effectiveness” can mean different things to different people. Our approach to assessing evidence combines what we know from scientific studies and the observations of unbiased experts. Strategies are generally assessed in terms of their effect on the factor(s) that drive health outcomes rather than their effect on health directly (e.g., strategies in the ‘Income, employment and wealth’ health topic are assessed for their effect on income, assets, or wealth).

Each reviewed strategy is assigned an evidence rating based on the quantity, quality, and findings of relevant research. When assigning ratings, we place the most weight on studies with designs that demonstrate causality; we consider study quality in conjunction with design. Strategies are rated for their effects on specified outcomes, labeled ‘Expected Beneficial Outcomes.’ Additional potential benefits suggested in our literature review are noted as ‘Other Potential Beneficial Outcomes.’

Evidence Rating	Meaning
	Strategies rated Scientifically Supported are most likely to make a difference. Multiple robust studies show consistently favorable results.
	Strategies rated Some Evidence are likely to work, but more research is needed to confirm effects. These strategies have been tested more than once and results trend favorable.
	Strategies rated Expert Opinion are recommended by credible, impartial experts but have limited research documenting effects. More research, often with stronger designs, is needed to confirm effects.
	Strategies rated Insufficient Evidence have limited research documenting effects. These strategies need more research, often with stronger designs, to confirm effects.
	Strategies rated Mixed Evidence have been tested more than once and results are inconsistent. More research is needed to confirm effects.
	Strategies rated Evidence of Ineffectiveness are not good investments. Multiple studies show consistently unfavorable or harmful results.

Learn more about our rating guidelines.

Disparity Rating

Analysts assign each strategy a disparity rating based on research about how a strategy may affect disparities (e.g., racial/ethnic, socioeconomic, or geographic disparities) for health and the social determinants of health. Analysts also consider each strategy’s characteristics, such as population, delivery method, and cultural considerations. A strategy’s impact on disparities may change depending on how it is implemented (e.g., tailoring a strategy toward a specific population).

Some strategies also feature an expanded disparity rating to indicate potential impact on disparities and describe the strength of the evidence supporting the rating. The expanded ratings are part of WWFH’s equity analysis.

Expanded Disparity Rating	Meaning
	Evidence, expert opinion, or intervention design suggests that these strategies have the potential to decrease or eliminate disparities between subgroups.
	Evidence, expert opinion, or intervention design suggests that these strategies have the potential to increase or exacerbate disparities between subgroups.
	Evidence or expert opinion suggest these strategies could increase and decrease disparities between subgroups.
	There is not enough evidence to assess a strategy’s potential impact on disparities.
Disparity Rating	Meaning
Likely to decrease disparities	Strategies that are likely to reduce differences in health outcomes (i.e., close a gap)
Likely to increase disparities	Strategies likely to exacerbate differences
No impact on disparities likely	Strategies that generally benefit entire populations