Information about publishing and citations  In the context of some discussions we are having at my university, it has become evident that some statistical information regarding publishing practices in the various areas of mathematics would be necessary to proceed---you know, facts. In particular, I would be immensely happy to know 


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*are there measurable and measured differences in the number of papers published by people working in different areas (think PDEs v. Algebraic Geometry v. Number theory v. Combinatorics; top level MSC groups, say)? Here I mean papers published by individual authors as well as collectively.

*are there measurable and measured differences in the number of citations gotten by papers in each area?; similar question about the out-degree in the citation digraph?

*what is the time profile of the citations to a typical math paper (ideally, broken by area again), whereby I mean: how are the citations to papers typically distributed in time?
Google has pointed to studies in which such comparisons are made between different disciplines (mathematics v. chemistry, say) but not at all between areas of mathematics.

Can anyone point to such information?

I would love to get hold of MathSciNet's raw tables (only papers, authors, subject area, citations) which would allow me to compute such things... (MathSciNet only has citation information since 2000, and I do not really know if that would make a representative sample for all-time statistics. It would be very interesting to have these kind of information diachronically, but I don't expect that data to be available)
 A: In addition to the previous responses:


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*Pure mathematicians are a lot worse about citing each other than applied mathematicians. Similarly, the threshold for being an author is quite high (I have seen (many) papers by X where the key lemma was proved by Y. In applied math or CS there is no question that Y would be a coauthor).

*In applied mathematics it is much more common for the advisor to be co-author on papers written by his/her grad students/postdocs (perhaps because of the greater influence of hard sciences, where the lab director's name appears on ALL papers published by people working in the lab. In the hard sciences the lab director's name is typically not the first, but in applied mathematics people use the pure math practice of alphabetical name order [at least more often than not]). This leads to a much greater average number of authors per paper, and so more publications and more citations. Unfortunately, the system is that a co-author of a five author paper gets full "citation credit".
If you look at the mathscinet list of top cited journals, you will see that the best pure math journals (Annals, Acta) are doing at best as well as some fairly generic applied math journals, which supports the above.
A: On Mariano's request I'm adding my comment on meta.MO as an answer here. This only concerns (part of) the first bullet point in the question.
There was an article Topical Bias in Generalist Mathematics Journals by Joseph F. Grcar in the december 2010 issue of the Notices of the AMS. According to the text, the statistics are based on  854,547 entries from the 2000-2009 period of the Zentralblatt database. Unfortunately the article remains silent on exactly how the data was gathered, but it might be a starting point for your own investigations.
For the convenience of the readers I take the liberty of reproducing the statistics most relevant for the present question from that article:

For more detailed information please follow this link or the ones provided above.
A: That was a comment, but it turned out to be too long ...
This does not exactly answers the first question. The distribution provided by Theo is the product of two functions: 1- the number of researchers in each domain; 2- the number of papers that a typical member of the given domain publishes each year. You cannot extract these two factors from their product only.
The answer to the second question raised by Mariano is definitively Yes. The number of citations depends not only on the quality of the work, but also upon the size of the community. And this size depends on several factors, among which the history (the older the domain, the larger the size). I have observed this for a long time within PDEs. This domain contains several sub-domains, mostly characterized by the type of the PDEs under study (elliptic, parbolic, hyperbolic, dispersive, ...) This is justified by the fact that the techniques are very different. Historically, elliptic equations developped first, thank to Hilbert's variational approach and then to the burst of the theory of distribution. Then parabolic, and later hyperbolic ones. The citation number of the world best researcher in hyperbolic PDEs (plenary speaker at ICM 2002) is about that of good ones in elliptic theory. It is about one tenth of that of world leaders in elliptic PDEs. There must be a similar bias in other domains.
