A study published in Science magazine by Nils Weidmann, a professor of political science at the University of Konstanz in Germany, found a correlation between lack of Internet access and political divisions between ethnic groups. It cross-referenced data about sub-national connectivity with information on the settlement regions of individual groups, showing how Internet penetration relates to political power. They concluded that excluded groups had significantly lower access compared to the groups in power, and that this can't be explained by other economic or geographic factors (like living in rural vs. urban areas). The results add a new layer to the understanding of how national governments control Internet use. 'Our findings underline one of the central impediments to "liberation technology," which is that governments still play a key role in the allocation of the Internet and can, intentionally or not, sabotage its liberating effects.'