Hi Stevan,
First I should note that I personally have nothing to do with this
study, I have only read Sarah's report. The author, Greg Schwartz
(gschwarz #@# as.arizona.edu) would certainly be a better source as to what
he is saying.
Certainly you may post my message about it.
To your question: Greg is referring to papers which have been deposited
in the ArXiv, normally astro-ph, thus they are self-archived in advance
of publication (preprinted). There are other avenues for astronomy
articles to be preprinted; he seems from the description not to be
taking them into account. In your terminology he notes that most of the
articles were submitted to the ArXiv after they were accepted (thus are
post-refereeing postprints); there is no requirement for this by any
astronomy journal, but it has long been the common practice, since
before preprints became electronic.
So the answer to your first paragraph question is YES!
Greg may know if there is a difference in citation rate for papers which
were deposited in the ArXiv before they were accepted (pre-refereeing
preprints) vs after they were accepted (postprints); this would help to
clear up the causality issue, as the preprints were self-archived earlier.
In any event this is a huge vote for the importance of self-archiving.
Best wishes
Michael
