On Fri, 8 Mar 2013 16:12:48 -0500, Simon Spero <[log in to unmask]> wrote:


>Field 245 shows some other curiosities:
>http://experimental.worldcat.org/marcusage/245.html
>
>Subfield 245 $k has 469,891 occurrences, but only 427,311 holdings;  this
>suggests that there are records included in the counts which have zero
>holdings.  These might be worth filtering out.

Something else that probably has little impact on the totals for the whole 
database, but which should be taken into account if investigation is 
segmented by publication date: my experience suggests that there is a 
sizeable number of duplicate records for pre-AACR cataloguing (that is, more 
or less, pre-1970 publications -- and I would say the period till 1980 and 
the onset of AACR2 also includes more duplicates than later.  I ascribe this 
to far less uniformity in cataloguing practice before AACR, and many such 
records having been converted retrospectively with little review, and loaded 
in bulk.  In addition, many foreign records, and British Library files, and 
the like, totally non-AACR/AACR2 and without any subject access, have been 
loaded in recent years.  The WorldCat database is quite a mixture; beware of 
relying too heavily on any simple tabulations.

Hal Cain
Melbourne, Australia
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