Here is a list of references which should help :)

Publications:

Eysenbach, G. (2011). Can tweets predict citations? Metrics of social impact based on Twitter and

correlation with traditional metrics of scientific impact. Journal of medical Internet research, 13(4).

Harnad, S., & Brody, T. (2004). Comparing the impact of open access (OA) vs. non-OA articles in the same journals. D-lib Magazine, 10(6).

Brody, T., Harnad, S., & Carr, L. (2006). Earlier web usage statistics as predictors of later

citation impact. Journal of the American Society for Information Science and Technology, 57(8), 1060-1072.

Thelwall, M., Haustein, S., Larivière, V., & Sugimoto, C. R. (2013). Do altmetrics work? Twitter and ten other social web services. PloS one, 8(5), e64841.

Priem, J., Piwowar, H. A., & Hemminger, B. M. (2012). Altmetrics in the wild: Using social media to explore scholarly impact. arXiv preprint arXiv:1203.4745.

Priem, J., & Hemminger, B. H. (2010). Scientometrics 2.0: New metrics of scholarly impact on the social Web. First Monday, 15(7).

Shuai, X., Pepe, A., & Bollen, J. (2012). How the scientific community reacts to newly submitted preprints: Article downloads,

twitter mentions, and citations. PloS one, 7(11), e47523.

Bik, H. M., & Goldstein, M. C. (2013). An introduction to social media for scientists. PLoS biology, 11(4), e1001535.

Galligan, F., & Dyas-Correia, S. (2013). Altmetrics: rethinking the way we measure. Serials Review, 39(1), 56-61.

Darling, E. S., Shiffman, D., Côté, I. M., & Drew, J. A. (2013). The role of Twitter in the life cycle of a scientific publication (No. e16v1). PeerJ PrePrints.

Fausto, S., Machado, F. A., Bento, L. F. J., Iamarino, A., Nahas, T. R., & Munger, D. S. (2012). Research blogging: Indexing and registering the change in science 2.0. PloS one, 7(12), e50109.

Mohammadi, E., & Thelwall, M. Mendeley readership altmetrics for the social sciences and humanities: Research evaluation and knowledge flows.

Journal of the American Society for Information Science and Technology. (in press)

Fenner, M. (2014). Altmetrics and Other Novel Measures for Scientific Impact. In Opening Science (pp. 179-189). Springer International Publishing.

Schlögl, C., Gorraiz, J., Gumpendorfer, C., Jack, K., Kraker, P., & Schloegl, C. (2013). Download vs. Citation vs. Readership Data: The Case of an Information Systems Journal. 14th International Society of Scientometrics and Informetrics Conference.

Retrieved from http://know-center.tugraz.at/download_extern/papers/issi2013_schloegletal.pdf

Davis, P. M., Lewenstein, B. V., Simon, D. H., Booth, J. G., Connolly, M. J., & Godlee. (2008). Open access publishing, article downloads, and citations: randomised controlled trial. BMJ: British Medical Journal, 343-345.

ISO 690

Links:

http://www.nature.com/news/formula-predicts-research-papers-future-citations-1.13881

http://www.barabasilab.com/pubs/CCNR-ALB_Publications/201211-01_Nature-1Percent/201211-01_Nature-1Percent.pdf

Not an answer, but a recommendation: The Regensburg University Library hosts "Bibliometrie 2014", a conference where issues such as the question you have posed may be discussed. See: http://www.uni-regensburg.de/bibliothek/veranstaltungskalender/bibliometrie2014/ for further information. Altmetrics topics as well as case studies will be in the program (to be published soon). You might also ask Christian Schlögl at KFU in Graz who is very knowledgeable on this topic ;-)

@ Elisabeth. More references. I hope you will find them useful.

http://www.citeulike.org/group/17557/article/11877310

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0048753

Thanks for your answers and the pointers.

Christian, for sure the Bibliometrics 2014 will be a great venue to discuss these ideas! Together with my colleague Peter Kraker I am also organizing a scientific track on Science 2.0 and Open Science at the i-Know conference (http://i-know.tugraz.at) where we aim to discuss these and related topics in more detail. 

I think one mayor challenge is (this holds for all types of social media research from my point of view) to understand what should we measure (not what can we measure), and also to understand the semantics of what you measure (e.g. what does a retweet really mean?).  Some standards and common agreements could help here.

https://asis.org/Bulletin/Apr-13/AprMay13_Liu_Adie.html

Dear Elisabeth,

if you want to do research on altmetrics, or social media metrics (I prefer this term, cause we already know that social media counts are no alternative to citations), Altmetric.com has been quite generous with providing their data for that. Just contact Euan Adie and his team to let the know what you have planned and ask!

Elsevier is also offering data but you would have to submit a proposal before they can tell you what they can/want to deliver: http://emdp.elsevier.com/

Then there is also the PLOS data, which is pretty detailed but of course limited to PLOS journals. Currently CrossRef is working on a metrics dataset for papers with DOIs.

If you are interested in research results, have a look at the PLOS ONE altmetrics collection, the altmetrics workshops, the recently launched 1:am and other relevant papers on arXiv, in JASIST.

Me and my colleagues at the University of Montreal and Indiana University also recently received a grant by the Sloan Foundation "to support greater understanding of social media in scholarly communication and the actual meaning of various altmetrics", so maybe you are also interested in what we are doing: crc.ebsi.umontreal.ca/sloan

If you are doing research on social media in scholarly communication, you might want to consider to submit to this forthcoming special issue in Aslib Journal of Information Management: http://www.emeraldgrouppublishing.com/products/journals/call_for_papers.htm?id=5754

http://www.ploscollections.org/article/browseIssue.action?issue=info:doi/10.1371/issue.pcol.v02.i19

http://altmetrics.org/altmetrics14/

http://arxiv.org/find/all/1/all:+altmetrics/0/1/0/all/0/1

crc.ebsi.umontreal.ca/sloan

http://www.altmetricsconference.com/

http://www.emeraldgrouppublishing.com/products/journals/call_for_papers.htm?id=5754

http://crosstech.crossref.org/2014/02/many-metrics-such-data-wow.html

Thanks Stefanie, this is very helpful!

Dear Elisabeth see it.

Conference Paper Does Research Gate show researchers’ performance? Case of Sh...

Dear Stefanie,

Do you suggest that altmterics is associated with social media metrics only? Because most of the studies have been conducted on Mendeley readership and CiteUlike etc. I find they are not pure social media sites. I think popular social medi sites such as Facebook and Research Gate happen to be less explored. Won't it be too early to call it social media metrics?