Does real time experience matter? Comparison of retrospective and in-situ spatial data in participatory mapping

Public Participation GIS is a widely used method in research, planning, and many other domains. Approaches to participatory data collection have traditionally taken place retrospectively, whereby a digital mapping platform is used for participants to elucidate their spatial through to and feelings. More recently, enabled by the proliferation of smartphones, data collection has also taken place in-situ, whereby participants report their spatial thoughts and feelings at their current location and time. There has yet to be any investigation into the implications of choice between retrospective and in-situ data collection, nor has there been any investigation into how comparable or compatible datasets collected using these methods might be expected to be. This paper addresses this shortcoming by providing a comparative analysis of retrospective and in-situ data collected in Olomouc, Czech Republic. Through a combination of theoretical, quantitative and qualitative approaches, the differences between the two methods are formalised along with their respective benefits and limitations. We find substantial differences between the results of the two methods, which have implications for methodological decision making. These implications are then examined in detail, providing critical guidance in the design of Public Participation GIS surveys for researchers and practitioners.