Bibliographic Correlations Help

Bibliographic Correlations

Contents

Introduction
How it Works
How to Search
Access Points

Introduction
The bibliographic correlations search screen is designed to assist catalogers in assigning classification numbers. It does this by looking at Library of Congress bibliographic data and determining the most common use of a given classification number, subject heading or name heading. The correlations search screen offers multiple access points for answering these types of questions:

What are the subject headings most frequently used with a specific LC classification number?
What are the LC classification numbers most frequently used with a specific subject heading?
What are the LC classification numbers most frequently used with a specific Dewey or National Library of Medicine classification number?

Unlike LC authority subject and name headings, all headings in the correlations system include any subdivisions that were applied in the bibliographic records. You do not need to enter any dash characters (--) between subdivisions to locate a particular combination of subject heading and its subdivisions.

How it Works
Bibliographic correlations are created by processing the the Library of Congress bibliographic database, extracting particular fields and making note of how many times certain combinations of fields appear together in the same record. Not all records or data elements are used. The restrictions include:

Any records with an abbreviated, partial or minimal encoding are skipped entirely. In other words, any records with a leader/17 value of '3', '5', or '7'.
Visual materials (leader/06) are not included in any correlations that involve LC classification numbers. However, visual materials are included for National Library of Medicine and Dewey numbers.
Only the first valid LC classification number that was assigned by LC is used in correlations.
Only the first valid NLM classification number that was assigned by NLM is used in correlations.
Only the first valid Dewey classification number that was assigned by LC is used in correlations.

Types of Correlations

Subject Heading Correlations
Only the first topical subject heading field (650 or 651) in each record is used to create subject correlations.

Subject Heading (Including Names) Correlations
The first 6xx field from each record is used to create these correlations.

Name as Creator Correlations
The 1xx field from each record is used to create these correlations.

When you search any of the correlations, the list that is returned is presented as a "top ten" list (i.e. the ten most common subjects for a given classification number or the ten most common classification numbers for a particular subject). Each result includes a number in parentheses that indicates the number of times that combination was found in the bibliographic database.

Because the system only returns ten correlations per subject, name or classification number, you may not find the particular combination you expected. It doesn't mean it is not in the database; just that it didn't make the "top ten" list. Also keep in mind that the eleventh entry (not shown) may have the same number of correlations as the tenth (the last entry that is displayed).

How to Search
Select the type of correlation you want to perform and input a search term. A drop-down list of matching entries will appear. Either select one of the items in the drop-down list or press Enter to start with the first matching term. When inputting headings, you don't have to input dashes when searching for subdivisions.

In the display of correlation search results, all of the headings and LC classification numbers are formatted as links that open a new tab with the appropriate LCSH, LCNH or LC class number browser.

Browsing correlations is very similar to using the LC Subject Heading browser. Please refer to that help page for more details.

Access Points

Search Type	Description
LC class number => Dewey class number	Locates the Dewey Decimal classification numbers most frequently used with a specific LC classification number.
LC class number => NLM class number	Locates the National Library of Medicine classification numbers most frequently used with a specific LC classification number.
LC class number => LC subject heading	Locates the LC subject headings most frequently used with a specific LC classification number.
LC class number => LC subject heading (including names)	Locates the LC subject headings (including names) most frequently used with a specific LC classification number.
LC subject heading => LC class number	Locates the LC classification numbers most frequently used with a specific LC subject heading or subject heading string.
LC subject heading => Dewey class Number	Locates the Dewey Decimal classification numbers most frequently used with a specific LC subject heading or subject heading string.
LC subject heading => NLM class number	Locates the National Library of Medicine classification numbers most frequently used with a specific LC subject heading or subject heading string.
LC subject heading (including names) => LC class number	Locates the LC classification numbers most frequently used with a specific LC subject heading or subject heading string (including names).
LC subject heading (including names) => Dewey class Number	Locates the Dewey classification numbers most frequently used with a specific LC subject heading or subject heading string (including names).
LC subject heading (including names) => NLM class number	Locates the National Library of Medicine numbers most frequently used with a specific LC subject heading or subject heading string (including names).
Name as Creator(1xx field) => LC Class Number	Locates the LC classification numbers most frequently used with a main entry heading (1xx field).
Name as Creator(1xx field) => Dewey Class Number	Locates the Dewey classification numbers most frequently used with a main entry heading (1xx field).
Name as Creator(1xx field) => NLM Class Number	Locates the National Library of Medicine classification numbers most frequently used with a main entry heading (1xx field).
Dewey class number => LC class number	Locates the LC classification numbers most frequently used with a specific Dewey Decimal classification number.
Dewey class number => LC subject heading	Locates the LC subject headings most frequently used with a specific Dewey classification number.
Dewey class number => LC subject heading (including names)	Locates the LC subject headings (including names) most frequently used with a specific LC classification number.
NLM class number => LC class number	Locates the LC classification numbers most frequently used with a specific National Library of Medicine classification number.
NLM class number => LC subject heading	Locates the LC subject headings most frequently used with a specific National Library of Medicine classification number.
NLM class number => LC subject heading (including names)	Locates the LC subject headings (including names) most frequently used with a specific National Library of Medicine classification number.

Libraries that use the Dewey Decimal Classification are encouraged to consult the latest Dewey Decimal Classification data found in the current print versions of the Dewey Decimal Classification and the WebDewey® online service available from OCLC. Check the OCLC web site at http://www.oclc.org/dewey/versions/default.htm for further information concerning these publications and online service.