Scale dimensions in public participation GIS: an overview for planning and research

Questions of spatial scale infiltrate Public Participation GIS (PPGIS) in multiple phases of the data collection from the design of a PPGIS survey to the use of the produced spatial knowledge. This paper provides an overview on how spatial scale and scale effects influence the use of PPGIS tools and the validity and usability of the spatial data they produce. The paper approached scale from two complimentary perspectives: as a concept in human geography and as an attribute of cartographic representation in geographic information science. This discussion is organized around three main viewpoints on scale and PPGIS, namely (1) scale in data collection denoting the geographic extent of the study area and the study population, (2) scale in survey design manifested in technical issues, cartographic representation, usability, and design of the mapping activities, and (3) scale and scale effects in the analysis of PPGIS data and the production of spatial knowledge. Together, these views on scale outline the main scale-related issues to consider when planning a PPGIS survey or working with secondary PPGIS data.