Health Impact Assessment (HIA)

Using evidence within HIA


What evidence is required?

The search for evidence often begins during the scoping stage of an HIA (identifying what to do and how to do it). The scoping stage involves, among other tasks, determining what information needs to be collected. This information will provide background and context to support the whole HIA, and point towards potential sources of evidence.

Setting boundaries for the collection of evidence

As with any task, it is important to be clear about the objective of the HIA. Scoping the boundaries of the HIA will often have a major impact on the type of information and evidence required:

  • Is the HIA rapid or comprehensive? – The defining feature of a comprehensive HIA is the collection of new primary data. This takes time, which is why most of the HIAs that are undertaken are rapid HIAs in which no new data is generated – only the best available evidence is used.
  • What is the geographical boundary of the HIA? – Boundaries can create problems for the collection of evidence. When communities are small, they often have very little statistical information at a small area level.
  • What is the timeframe for the HIA to deliver? – Evidence must be collected and be made available for analysis at the right moment. This is particularly challenging for rapid HIAs, when there is little time for the whole HIA, let alone for searching for evidence. Practitioners should be realistic about what evidence sources can be accessed in the available time.
  • What skills are there in the HIA team? – Finding evidence can be difficult, and obtaining access to "information specialists" can be a real advantage. Such people may exist in local health departments, universities or libraries. Some evidence sources require a level of analysis before they can be used in an HIA; this analysis requires time and skill.
  • What are the values of the steering group regarding the use of evidence? – Do the members of the steering group value community experience at the same level as scientific evidence? And how will they manage conflicts in evidence that may arise?
  • Key decision-makers will have to be engaged. Who are they? – Knowledge about decision-makers helps work out the type of evidence that needs to be provided. This does not mean telling decision-makers what they want to hear, instead it is about providing evidence in a format (qualitative or quantitative) that is useful for the decisions that have to be taken.
  • What is the target group of the proposal? – The target group may have low literacy levels, speak different languages, be difficult to contact, have little or no community representation, be culturally excluded from mainstream society and have diverse or opposing viewpoints. Consideration of all these issues is required when collecting information from such peoples. Culturally sensitive methods will be required, often using people from the communities to assist in the collection of evidence.
  • Will the HIA be monitored and evaluated? – If so, specific information must be collected at the start of the process (for example, baseline data), during the HIA (process information), at delivery of the HIA (impact information) and during the implementation of the proposal (monitoring and outcome information).
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