The selection of the types of solutions and evaluated cases that are incorporated into the Evidence Bank is based on one main criterion: the existence of impact evaluations carried out according to international standards of methodological rigor that allow the establishment of causal inference relationships. 
Impact evaluations seek to measure whether changes in the well-being of individuals (for example, a reduction in robberies) can be attributed to a specific project, program or policy (for example, a hot spots policing program). This focus on attributing causality is an intrinsic feature of impact evaluations. The main challenge in an evaluation of this type is therefore to identify the causal relationship between the program or policy and the outcomes of interest. To find out more about different impact evaluation methods, see Impact Evaluation in Practice.
In order to systematize the results of individual studies related to a specific type of solution, there are Systematic Reviews, a form of qualitative research that seeks, based on secondary data, to consolidate the results of relevant studies, always adopting strict criteria to select the specific studies that will be considered in the analysis. In some cases, these reviews are accompanied or complemented by meta-analyses, a quantitative method used in the systematization of evidence whose main objective is to produce a synthesis of the findings of a series of primary/empirical studies.