Scale of Questions and Scale of Answers: The Role of Remote Sensing for Public Health Policy

Marcia C. Castro, Harvard University

Currently, imagery resolution can be as precise as 0.61m or as coarse as 8Km. While one could argue that any image could be used for policy purposes, different questions would be answered by each sensor. Applications at coarse resolutions are useful to offer an overall picture and to identify potential critical areas/processes that need further investigation. These studies are not designed for decision making or for guiding spatially targeted interventions. Although this seems intuitive, the literature shows that, unfortunately, the issue of scale is largely overlooked. In this paper we describe the potential application of varied imagery, suggesting their suitability at different levels (national, regional, district, local) and environments (urban/rural). Although the paper has a focus on public health, we ultimately propose a grid that offers guidelines to social scientists on the appropriate scale for purposes of planning, monitoring, and assessment of policies and processes operating at different levels.