The format for citing data sets is still evolving. Below is an example for the most common style manuals used at ASU. The example is taken from the ASU Library Digital Repository. It is still assumed that data sets are attached to reports, dissertations and other published works.
Chicago Manual of Style: Depends on the format of the source (paper or digital), published or unpublished, and whose data (private, institutional, or governmental) it is. If the data is included in a publication, you follow the citation style for that type of publication. If it is a data set, the style would be to use the author and name of the file in the repository.
Overman, William, "Study of a Night Sky Radiator Cooling System Utilizing Direct Fluid Radiation Emission and Varying Cover Materials. ExcelDataFiles.zip." (master's thesis, Arizona State University, 2011), https://hdl.handle.net/2286/R.A.93277
Modern Languague Association (MLA): Does not have a specific format for data or statistics. This relies on the majority of data cited to be in a publication.
Overman, William, "Study of a Night Sky Radiator Cooling System Utilizing Direct Fluid Radiation Emission and Varying Cover Materials. ExcelDataFiles.zip." MS thesis, Arizona State University, 2011. ASU Digital Repository. Web. 3 July 2013.
APA (Publication Manual of the American Psychological Association): Look at the examples in 7.08 and 7.09, there are variations so look carefully.
Examples:
Rightsholder, A.A. (Year). Title of Program (Version number) [Description of form]. Location: Name of producer.
Rightsholder, A.A. (Year). Title of Program [Description of form]. Retrieved from http://xxxx
ASU example:
Overman, William. (2011). Study of a Night Sky Radiator Cooling System Utilizing Direct Fluid Radiation Emission and Varying Cover Materials [Data file]. Retrieved from https://hdl.handle.net/2286/R.A.93277