Geographic information underpins so much of what we do today on the internet. By knowing the location of a tweet, a profile, or any other user-entered information, we can build services and software that is micro-targeted at user needs: for example dating sites, advertising, and search results.
For that reason, Stefano De Sabbata and I have done some work to understand the biases embedded in the databases that we use to create geographic ground truths.
I've written up some of the findings for a post in The Guardian (Graham, M. 2015. The Hidden Biases of Geodata. The Guardian Apr 28, 2015.), and you can read more about the research in a pre-print of our forthcoming paper:
Graham, M. and De Sabbata, S. 2016. Mapping Information Wealth and Poverty: The Geography of Gazetteers. Environment and Planning A. (in press).