  The study explores the citedness of research data, its distribution over time
and how it is related to the availability of a DOI (Digital Object Identifier)
in Thomson Reuters' DCI (Data Citation Index). We investigate if cited research
data "impact" the (social) web, reflected by altmetrics scores, and if there is
any relationship between the number of citations and the sum of altmetrics
scores from various social media-platforms. Three tools are used to collect and
compare altmetrics scores, i.e. PlumX, ImpactStory, and Altmetric.com. In terms
of coverage, PlumX is the most helpful altmetrics tool. While research data
remain mostly uncited (about 85%), there has been a growing trend in citing
data sets published since 2007. Surprisingly, the percentage of the number of
cited research data with a DOI in DCI has decreased in the last years. Only
nine repositories account for research data with DOIs and two or more
citations. The number of cited research data with altmetrics scores is even
lower (4 to 9%) but shows a higher coverage of research data from the last
decade. However, no correlation between the number of citations and the total
number of altmetrics scores is observable. Certain data types (i.e. survey,
aggregate data, and sequence data) are more often cited and receive higher
altmetrics scores.
