  This paper is a first draft of the introduction to the special issue on
volunteered geographic information published in Computers, Environment and
Urban Systems (2015, 53, 1-122). In this short paper, I put georeferenced big
data (hereafter, big data) such as tweets locations in comparison with small
data such as census data in terms of data characteristics, and further argued
that big data differs fundamentally from small data in terms of data analytics,
both geometrially and statistically. I would like to thank my colleague Dr.
Jean-Claude Thill, who expanded the draft towards a broader scope.
