Tables of Contents in the Catalog and Their Impact on Usage

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Tables of Contents in the Catalog and Their
Impact on Usage Karen D. Miller Monographic/Digi
tal Projects Cataloger Michael S.
Babinec Assistant Head, Bibliographic Services
Dept. Northwestern University Library Evanston,
Ill. 60208
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• About Northwestern University Library
• NUL is a research library with approximately 4.8
  million volumes held on campuses in Evanston and
  Chicago, Illinois.
• TOC fields have been added to bibliographic
  records since 2002 using Blackwell Book Services
  TOC service.
• Over 61,000 Blackwell TOCs have been added to
  MARC 505 fields at NUL.
• At 1.05 per record, we wanted to determine if
  they made a statistically significant difference
  in circulation.

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TOC in the catalog
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• Study Objectives
• Sought to replicate a 1997 study done at the
  University of New Mexico Health Sciences Center
  Library by Ruth C.T. Morris
• Hypothesis that the inclusion of Table of
  Contents (TOC) fields in bibliographic records
  influences circulation

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• Study Objectives
• Do other factors interact with the TOC field to
  influence circulation?
• We examined the effect of
• Library location
• Subject matter, indicated by Dewey class
• Year of publication

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• Previous studies
• Focused on smaller collections, homogeneous
  collections. One study used a health sciences
  library, one a collection of IEEE conference
  proceedings.
• Used smaller sample sizes than NULs study (some
  as small as 180 books).
• One looked at any kind of enhancement, including
  TOC fields, book covers, author biographies, and
  reviews.
• All determined that TOC enhancement increased
  circulation and several concluded that prior
  circulation was also a factor.

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• About the study
• Study sample randomly chosen from over 5,000
  bibliographic records with TOC enhancements
  available from Blackwell
• 14 month study period June 2006 through July
  2007
• 7-month study period was long enough for patrons
  to check out and return most books
• Both periods encompassed roughly similar
  academic cycles
• In-house browse data not as robust as
  check-out data

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• Defining the sample
• We included only bib. records
• For monographs
• From circulating locations
• With circulating status
• With Dewey numbers

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• Refining the sample
• We excluded
• Course reserve material, as it needs no help to
  circulate!
• Books assigned to the New Book Alcove and to
  study carrels
• Books held at a Circulation desk, which cant
  easily be browsed
• Any bibliographic record with more than one
  associated item

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• Study Methodology
• 4,633 bibliographic records split into two
  groups, stratified by Library Location and Broad
  Dewey Class (at the hundreds level).
• Study Period 1 June - December 2006 no TOC
  enhancements were added so that we could collect
  circulation (check-out) and browse (in-house
  usage) statistics.
• Study Period 2 January July 2007 TOC
  enhancements were added to Group 2 (the test
  group) but not to Group 1 (the control group).
• At the end of the study, we compared circulation
  increases for the two groups.

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• About the Study
• We used SPSS for Windows to perform the
  statistical analysis and used outside statistical
  review of the sample stratification, study
  design, analyses, and interpretation.
• Gary Strawn, our systems librarian, added a MARC
  035 subfield that indicated a bibliographic
  record was in the study and to which study group
  it belonged.
• Library IT assisted in pulling data from the
  Voyager back-end databases.

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Library Location distribution
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Distribution of Dewey Classes
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Distribution of Year of Publication
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• Study Methodology
• We looked at several ways of measuring results
• A binary variable indicating whether a book had
  any use (circulation plus browsing) in Period 2.
  This is the variable that the University of New
  Mexico used.
• A binary variable that measured whether there
  was an increase in the number of times a book was
  checked out of the library from Period 1 to
  Period 2.

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• Study Methodology
• We examined and dismissed several approaches
• using in-house browse data. While nearly 40
  of books were checked out, fewer than 18 had
  browse charges
• measuring how much circulation increased between
  the study periods

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• Statistical analysis
• After examining the Year of Publication
  distribution, we narrowed our study down to 3
  variables
• Study Group (whether a bibliographic record had
  TOC enhancement or not)
• Library Location, with 5 values
• Broad Dewey Class (hundreds level)

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• Statistical analysis
• Relationships between each of the independent
  variables and the dependent variable were
  examined and each had merit on its own.
• Chi-square tests indicated that all but the
  Dewey Class were independent predictors of
  circulation increase.

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• Statistical analysis
• Logistic regression was used to analyze the data
• well suited to categorical independent variables
  and a binary outcome variable (increase or no
  increase)
• measures the likelihood of a certain event
  occurring, in this case, an increase in
  circulation.
• likelihoods are expressed with respect to
  different categories of the independent variables
  in the model.

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• Statistical analysis
• Dewey classes not evenly distributed and too
  closely associated with Library Location
  dropped from final model.
• Residual analysis was performed and showed
• No patterns of poor fit
• No evidence of individual cases that influenced
  the model, but the Main Library influenced the
  model due to the number of cases it represents in
  the study data.

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• Study results
• Enhancement of catalog records with TOC fields
  the most significant factor in determining
  whether a book had an increase in circulation.
• A book with a TOC-enhanced Voyager record was
  24 more likely to have a circulation increase
  than a book without a TOC-enhanced record.
• Location is also a significant predictor of
  circulation increase-- Math the most likely
  Location to see an increase, then Africana, with
  Schaffner the least.

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• Study results
• Replicating the University of New Mexico study
  We looked at only whether a book was used or not
  during the second period of the study
• TOC enhancement was still significant, making a
  book 22 more likely to be used, but not as
  significant a factor as whether the book had been
  used previously or not.
• A book that had previously been used in-house or
  checked-out was 57 more likely to be used again
  than a book that had not been removed from the
  shelf before.

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• Outstanding Questions
• Isnt the TOC enhancement just as likely to
  convince a patron that a book is not what she or
  he wanted as it is to get the book checked out of
  the library? We dont know and maybe well never
  know. We cant read minds, only databases.
• Our speculation is that the TOC enhancements
  result in an increase in recall, which turns up
  books that might not have been otherwise. Whether
  this results in a corresponding increase in
  precision is still unknown.

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• Additional Research
• Our next study will examine keyword searching.
  We hope to answer
• What percent of keywords were found only in the
  TOC field?
• What percent were found only in the subject
  heading fields?
• What percent were found in transcribed fields?
• We hope to see you next year in Chicago with the
  exciting conclusions of our keyword search study!

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• Many thanks to.
• Gary Strawn, Authorities Librarian/Library
  Systems Analyst, for help interpreting Voyager
  coding and SQL.
• Stu Baker, Assistant Director of Library
  Technology, for giving us the go-ahead to pester
  the Voyager DBA and Gary Strawn.
• Suzette Radford, Head of Circulation Services,
  for guidance on where to get data and how to
  interpret it.
• David D. Morris, Director of Statistics at
  WebbWrites Clinical Writing Statistics
• David P. Nichols, Master Statistician, SPSS Inc.
  

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Please direct questions and comments to Karen
D. Miller Monographic/Digital Projects
Cataloger k-miller3_at_northwestern.edu Michael S.
Babinec Assistant Head, Bibliographic Services
Dept. m-babinec_at_northwestern.edu Slides are
online at http//presentations.ala.org Papers
will be published as part of the ALA conference
proceedings.