Statistical data is collected from surveys, polls, interviews, studies, reports, etc. by government entities, academic institutions, and research centers for use in research and record-keeping. The data can be numerical or nominal information about populations, locations, and more.
A data set is a file of collected data, structured in a way that allows the reader to draw comparative relationships. Statistical sources like those linked below present data in a way that can be searched and interpreted, and reinforce academic research and writing.