© Tefko Saracevic 1

Types & structures of information resources

What is out there for searching and what’s under

the hood?

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Definitions• resource – Encarta Dictionary

“Source of help…somebody who or something that can be

used as a source of help or information… adeptness at finding solutions to

problems”• database – Webopedia.com

“A collection of information organized in such a way that a computer program can quickly select desired pieces of data. You can think of a database as an electronic filing system.”

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Definitions (cont.)

• Information databases are organized by fields, records, and files. A field is a single piece of information; a record is one complete set of fields; and a file is a collection of records. For example, a telephone book is analogous to a file. It contains a list of records, each of which consists of three fields: name, address, and telephone number.

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Relations• Terminology can be confusing & not consisted

- so beware & do your own translation– Provider: a producer of databases; there are great

many providers covering many fields• e.g. Dept. of Education produces ERIC – abstracts &

indexes educational materials (articles, reports)

– Vendors or aggregators: organizations or companies that get databases from providers & organize them for searching; there are a number of vendors; some providers are their own vendors

• e.g DIALOG gets over 400 databases from a variety of providers, (among them ERIC) & then organizes them for searching

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Example of a vendor: DIALOG

• acquires databases, from information providers at a fee

• organizes content according to given structures

• describes the content– done in Bluesheets, a most important search tool

for you

• provides given searching capabilities– you have to master them for effective searching

• creates some own files – e.g super indexes• provides you access at a fee

– there is no such thing as free lunch

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BTW – why DIALOG?• Why do we use DIALOG for so many

exercises? Several reasons– oldest and largest surviving vendor– most comprehensive set of databases– has a well developed instructional program– but most importantly: serves as a good test

bed to develop searching skills that are generalizable

– what you will systematically learn from using DIALOG can be translated to all searching• & you get an insight into problems with searching

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Other vendors/aggregators• Good number of other

vendors is around– the landscape is

constantly changing– some available through

RUL – examples (examine!)

• LexisNexis• Factiva• ScienceDirect• EBSCOhost• Ingenta … and on

– some incorporate databases from producers, others create own databases from myriad of sources

• confusing?? wait, there is more…

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Types of information databases

• Many types are available:– Bibliographic– Numeric– Full text– Directory– Image– Sound– Multimedia– Real time

• Some that are in DIALOG are also available elsewhere or on their own

• Some vendors have exclusive right to some databases

• Many you find in RUL

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Examples of databases• Over 200 available at RUL – examples

that are relevant to library and information science

• Library and Information Science Abstracts • Library Literature and Information Science • Information Science and Technology Abstracts • ERIC• IEEE Xplore• ACM Digital Library• but others also cover materials of interest e.g

– Web of Science – INSPEC

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a BIG problem• In DIALOG & some other vendors you

can search a number of databases at the same time – so called federated searching– or in DIALOG search Dialindex – a meta

index of databases• BUT in RUL & elsewhere there is no

federated searching– you have to search each database

separately• someday there will be federated searching, but

at present do not hold your breath

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as would imagine …

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Now unto structures – getting under the hood

• Each database type has its own structure– why? to describe various parts of content for

computers to recognize• you can recognize that a section of a document is a

title, but computer has to be told that a title is a title

• so that it can (among others) search for terms in a title when you request so

• Parts of documents (or objects in databases) are labeled as to as to content or function

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Labeling schemes • Many structure schemes were developed that

prescribed what to label & what to call the label – meta languages– by providers, vendors, organizations, authorities– in different subjects, domains– for different types of objects

• Meta tags are used on the web – to describe & index– semantic web is in development, to further enable

description of and searching for meaning

• MARC is a form of meta language• To use these schemes for effective searching you

have no choice but to get familiar

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Transparency of structures• In some databases description of

structure is readily available – even though it may look forbidding,

complicated• good example: Bluesheets in DIALOG

• In others, structure is there but has to be discovered by surmising– even in

• But clever, appropriate use of structure in searching is key to effective searching

…

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Example: file 438 BluesheetLibrary Literature and Information

ScienceDescribes the

content of the file

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file 438 fields- each is searchable

Sample record:indicates structure

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file 438: fields in Basic Index

Basic index is searched by default –

examples how to search fields in basic index

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file 438: fields in Additional Indexes

Additional index is searched by indicating the field to be searched –

examples how to search them

If you want to search the latest update

only, add to search UD=9999

Neat trick:

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file 438: fields inLimit

Searches can be limited to cover documents with given attributes –

examples how to limit searches

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file 438: additionaluses of structure

Results can be sorted or ranked by given fields –

examples how to sort or rank results

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file 438: options in displaying of results

Results can be displayed in a number of ways –

examples of available formats

But watch out! In real life some formats are free other cost $$$$!

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Economics – tail that wags the whole dog• In class DIALOG searching is free

– & you can use it for class exercises, nothing else

• In real life DIALOG (as every other vendor) has an elaborate economic structure – different files have different price tags for use– time of use is calculated in DialUnits

• a Byzantine structure of charges beyond understanding

– in different files different formats have different price attached• some are rely hefty!

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Where to find all about structure?

• In DIALOG in BlueSheets– consult often! and again! and again! and

again!– files have similarities and differences in

structure – BlueSheets show that• For other vendors:

– some have similar description as BlueSheets

– some have to be dug up & surmised– in some revelation comes from checking

what is available in advanced searching or in tips for searching

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Structure in search engines• Mostly not readily apparent

– but all have capabilities to be used in searching

• Again: revelation comes from checking what is available in Advanced Search, Search Features, Search Tips, Help, & the like

• Most users do NOT take advantage of using available structures in searching– professional searchers do

• part of their tool kit & competencies

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Example: structure from Advanced Search

Records are

structured at

minimum by these

fields

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Another example: structure from Advanced Search

Records are also

structured at

minimum by these

fields

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Similarities & differences• All vendors & search

engines have a basic search by default & an advanced search– but defaults &

advanced capabilities differ & have to be confirmed for each

– once you learn, you will apply variations on the theme

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Similarities & differences …• All vendors & search

engines have basic & advanced Boolean-type search capabilities– but how it is done &

bells and whistles differ

– once you master concepts you can then do an AHA! when you encounter a variation & then translate

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Similarities & differences …• All vendors & search

engines rank output results– but how it is done differs– DIALOG uses LIFO – Last

in First Out as default, but also allows for other ways

– search engines use ranking by relevance, clustering, PageRank … criteria

• not easy to discern

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Similarities & differences …• Most users

– do not know or care about structure

– do not search beyond default capabilities

– do not look beyond one or two pages of results

– miss many potentially relevant results

– do not know what is under the hood

• Professional searchers– know that structure is

very much connected to searching

– learn about & use available structures

– understand defaults & use advanced capabilities as necessary

– know “tricks” for not missing stuff or not getting to much or to much junk

– explore in order to learn what is under the hood

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In conclusion!

Searching is more art than science, but an art that needs a lot of knowledge what is behind it

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