https://www.sciencedaily.com/releases/2020/04/200409093926.htm

Traditional economic recovery estimates, such as surveys and interviews, are usually costly, time-consuming and do not scale-up well. However, researchers from Bristol's School of Engineering Maths and Department of Civil Engineering show they were able to accurately estimate the downtime and recovery of small businesses in countries affected by three different natural hazards using aggregated social media data.

The method relies on the assumption that businesses tend to publish more social media posts when they are open and fewer when they are closed, hence analysing the aggregated posting activity of a group of businesses over time it is possible to infer when they are open or closed.