How can mobility data be used to evaluate urban green space interventions? A synthetic control analysis of wildflower planting in Liverpool, UK (2021–2022)

Mobility datasets (i.e. mobile phone-derived flows of people) may offer more granular information on utilisation of urban spaces compared to traditional research datasets. However, there are few existing case studies on their use limiting our understanding of the unique challenges they bring to their effective use. In this study, we combine empirical and methodological work to explore how mobility data can contribute to evaluating the impact of place-based interventions. We evaluate the impact of wildflower planting on urban green space utilisation in Liverpool (UK). Our findings suggested that wildflower sites had a greater number of visits than expected in May, with lower visits thereafter. In the 3-month post-intervention, there was a negligible change in urban green space visits (effect size −1.0%, 95% confidence interval −32.3% to 50.6%). Interpretation of these findings was constrained by several methodological and data limitations that made it difficult to understand the utility of analysing mobility data to evaluate place-based interventions. Whilst mobile phone-derived mobility data may offer some solutions to the limitations of alternative study designs, greater research is needed to address the significant challenges that using these data poses.