Generally, there are two broad methods to measure impact of interventions tackling disinformation: quantitative and qualitative.
Qualitative methods seem less suited for top-down interventions and well suited for peer-to-peer interventions since they require a trust relationship to acquire relevant responses. Peer-to-peer interventions tend to create circumstances in which people feel heard, seen and safe, and feel that they belong. Top-down interventions require a hierarchical setting in which trust is a bonus rather than a given.
Quantitative methods seem less suited for peer-to-peer interventions since for this type of interventions change is a long-term, delicate, interactive process. For top-down processes quantitative methods are crucial because they constitute the most important verifiable feedback information.
In effect, this means that top-down interventions require ante well-defined success criteria that are to be measured post quantitatively, while peer-to-peer interventions require a trust access to their target groups to be able to ongoing measure effects qualitatively.