Table 2 Domains Assessed to Determine Strength of Evidence

Study design

We considered experimental and quasi-experimental designs to improve the strength of estimates of intervention effectiveness. We considered experimental designs to provide the highest-strength evidence. However, other methods may be more important for assessing strength of claims on how and why the intervention works.

Quality

We used the Mixed Methods Appraisal Tool checklist to score the quality of the literature on routine immunization data use that qualified as evidence. ‘Strong’-quality studies scored 75–100 %; ‘Moderate’-quality studies scored 50–74 %; ‘Weak’-quality studies scored 0–49 %.

Number of studies and their agreement

A greater number of studies with similar findings improved our certainty in those findings. Studies with conflicting findings weakened the strength of evidence.

Context dependence

We considered evidentiary claims for highly context-dependent interventions to have lower strength, or we specified the conditions under which the claims hold true. For example, for certain interventions composed of multiple strategies, it was not possible to fully disentangle the effects of individual strategies. In such cases, we recognized how other strategies may have influenced the overall effect of the intervention.