An extensive analysis of the presence of different altmetric indicators
provided by Altmetric.com across scientific fields is presented, particularly
focusing on their relationship with citations. Our results confirm that the
presence and density of social media altmetric counts are still very low and
not very frequent among scientific publications, with 15%-24% of the
publications presenting some altmetric activity and concentrating in the most
recent publications, although their presence is increasing over time.
Publications from the social sciences, humanities and the medical and life
sciences show the highest presence of altmetrics, indicating their potential
value and interest for these fields. The analysis of the relationships between
altmetrics and citations confirms previous claims of positive correlations but
relatively weak, thus supporting the idea that altmetrics do not reflect the
same concept of impact as citations. Also, altmetric counts do not always
present a better filtering of highly cited publications than journal citation
scores. Altmetrics scores (particularly mentions in blogs) are able to identify
highly cited publications with higher levels of precision than journal citation
scores (JCS), but they have a lower level of recall. The value of altmetrics as
a complementary tool of citation analysis is highlighted, although more
research is suggested to disentangle the potential meaning and value of
altmetric indicators for research evaluation