Toward a methodological toolkit to mitigate the evaluator's dilemma: Assessing pastoralist rangelands management in Northern Tanzania

Biodiversity conservation is a “crisis discipline,” with funds often directed toward urgent needs rather than evaluations. Accordingly, researchers tasked with an impact evaluation in conservation can face the evaluator's dilemma: determining the potential impacts of project activities while lacking an ideal study design. Using as an example a USAID‐funded intervention to improve pastoralist communal rangeland health in Northern Tanzania, we show how methods relatively novel to the field of conservation evaluation—directed acyclic graphs and item response theory—can help to mitigate this dilemma. We find that the perceived quality of rangeland commons governance after project completion is positively associated with, and potentially causally related to, positive outcomes in the perceived successes of management and remotely sensed assessments of changes in bare land cover pre and post intervention. This is consistent with the development partner's theory of change and extends our knowledge of which factors mediate whether and how commons management interventions work. Our methodological tools demonstrate how messy and complex data can be productively leveraged, and why unequivocal causal effects cannot always be determined. More broadly, we demonstrate valuable additions to the evaluator's toolkit that can improve the validity of inferences when resources allocated to evaluation are constrained.