A recent publication on using social media to identify how many individuals are in small populations, e.g. people living in a tower block.Work factors in a range of contributing factors, e.g. age, language spoken, socio-economic information etc

R.O. Sinnott, W. Wang, Estimating Micro-Populations through Social Media Analytics, accepted for Journal of Social Network Analysis and Mining, April 2017.

Results are pretty impressive with predicted accuracy and known statistics for small regions (see below!)