Phases of HIA 3. Assessment
During the assessment phase, evidence is gathered on the effects of the policy or program on health determinants and health outcomes. Typically the only new data generated in health impact assessments is through qualitative data collection. This may include focus groups, key informant interviews, participatory observation etc. It is often not practical or necessary to generate new quantitative data. Existing data from the literature is often sufficient. Systematic reviews of available research are an effective way to gather information.
Health impact assessment needs to consider multiple potential effects and pathways, both positive and negative. Whether the analysis is quantitative or qualitative, the logic of the analysis is similar to that used in risk analysis. It should consider both how the proposed policy or project will change health-related exposures in the population and how it might change the affected population. For instance, a mixed use housing project may entail changes in exposure to air pollution, traffic, mobility, noise and social networks. It could also attract new residents and displace some current residents.
Assessment in HIA is often iterative. Assessments are refined as feedback is received by expert reviewers and stakeholders. To facilitate review, it is essential that the methods, assumptions and data sources used in the assessment are made explicit and stated clearly with minimal use of jargon.