2.4: What Does “Evidence-Based Practice” Mean?

We often use this term “evidence-based practice” in public health when it comes to policies, programs, or healthcare services. A lot of people have what seem to be great ideas on how to solve health problems, but as the saying goes “ideas are a dime a dozen”. How do we know if this idea will really work? And especially when it comes to funding with government grants - which are taxpayer dollars - we need to make sure that we’re not just throwing money at random ideas and hoping they are effective.

Evidence-based practice means “systematically finding, appraising, and using evidence as the basis for decision making” (Seabert et al., 2021, p. 115). This means that before we create programs or propose policies, we should gather as much evidence on the problem and potential solutions as possible, assess the applicability of available evidence to the current problem, and then use this knowledge to help guide decisions on whether or how to move forward. There may have been programs or policies similar to our ideas that have already been tried in the target population, or in other communities. What if there is evidence that this particular solution doesn’t work well? We certainly wouldn’t want to propose a program or policy that had already been proven to be ineffective. Or perhaps there is evidence that certain implementation methods were more effective than others. We would want to use that insight to make our interventions or policies more likely to work.

Figure \(\PageIndex{1}\): (Photo by CDC on Unsplash)

Two types of evidence can be used in this process: objective and subjective. Objective evidence comes in the form of scientific studies and data collection, whereas subjective evidence may be in the form of expert advice or personal experiences and observations from community stakeholders. Typically objective evidence includes things that can be measured or observed, and is often expressed in numbers or percentages. Subjective evidence includes personal accounts, individual experiences and stories - this type of evidence is often based on the perceptions of the person observing something or being interviewed. In practice, objective evidence is often valued more highly than subjective evidence, in large part because well-done research uses several methods to reduce bias and misinterpretation. Objective data also tends to be more reliable than individual experiences or opinions. For example, a community member might perceive that homelessness is not a problem for their city, because they used to see many tents and makeshift shelters on sidewalks in their neighborhood, and recently the sidewalks have been clear. But the objective data may show a more complex picture: perhaps the individuals who had been living in those makeshift shelters had been forced to relocate, but were still unhoused.

Care should also be taken in interpreting research and applying objective evidence to different situations. Just because a particular program worked for one community doesn’t mean it will work in another. Subjective evidence from stakeholders in the community, or professional experience from public health workers, should still be valued. For example, a community health worker may know from their work that many of the unhoused are not living on the street - they are living in their cars or “couch-surfing”, and therefore they might not be aware of or have access to social services. Scientific studies may leave out certain populations, or we may not yet have scientific research available for a specific health problem. Therefore, it’s important to consider all sources of evidence when using an evidence-based approach to public health.