Google Scholar

Access to scholarly content:

• Journal articles

• Books

• Preprints

• Technical Reports

• OAI data

• A&I Services (publicly available)

---

How it works

• GS identifies "scholarly content" using simple rules based common formats and traits of scholarly papers

• They extract title, author, abstract & references to build an index

• Once papers and references are interlinked, algorithms create indexes and rankings

---

Google weighting factors

• Google takes

• The phrase hits (the Xs),

• The adjacency hits (the Ys),

• The weights hits (the Zs), and

• About 100 other secret variables

• Throws out everything but the top 2,000

• Multiplies each remaining page's individual score by it's "PageRank"

• And, finally, displays the top 1,000 in order.

Patrick Crispen (CSU Fullerton).

---

Google PageRank

• There is a premise in higher education that the importance of a research paper can be judged by the number of citations the paper has from other research papers.

• Google simply applies this premise to the Web: the importance of a Web page can be judged by the number of hyperlinks pointing to it from other pages.

Source: Google Hacks, p. 294

---

The PageRank Algorithm

Where

• PR(A) is the PageRank of Page A

• PR(T1) is the PageRank of page T1

• C(T1) is the number of outgoing links from the page T1

• d is a damping factor in the range of 0 < d < 1, usually set to 0.85

Source: Google Hacks, p. 295

---

GS Ranking Algorithms

• Factors

• Keyword/Author

• Publication ranking

• Number of citations

• Outgoing and incoming

• ONLY from the GS corpus

---

Human Genome

• Google

• Searching WWW (millions of pages)

• Number of hits: 5M+

• Top results:

• Genome centers

• research institutions

• Google Scholar

• Major publishers + A&I's (100k sources)

• Number of hits: 260k

• Top results:

• Landmark papers from Science & Nature with links to free versions of full text

---

Access to Journal Content

• Provides access to publisher's websites

• TOC's, abstracts, full text if available

• Elsevier, Wiley, major scholarly pubs

• Not normally spidered by Google due to their "anti-cloaking" policy

• Articles on personal websites, institutional archives, e-print databases

---

GS caveats

• Fairly random, incomplete selection of materials available

• Only a starting point for advanced searches

• Lacking content in the Social Sciences & Humanities

• Building its own lexicon based on citations & frequency of word appearance

---

GS Desired Features

• Filtering / Screening capability

• (metadata filters)

• Sorting options

• By availability (OA vs. Controlled)

• Searching only select content

• Specific publishers

---

Things GS won't tell us

• Search algorithm (proprietary)

• How it defines "scholarly content"

• How often the data is updated

• Sources

• How/when/if GooglePrint Content will be added

---

Issues

• Threat to the A&I Services; Libraries?

• Competition from YahooSearch / Scopus

• Where are the ads?

• Censoring / filtering

• Does quality reflect naturally in the way items are ranked

• Versioning problem

• Link resolver obsolescence

---

Link Resolvers for Local Content

• Follows Open URL standards

• Requires institution to have LR installed

• Default access for on-campus users

• Offsite users can select manually

• Local content ranked higher

• Some problems with connectivity

• PMID, DOI's work well

• Some eprint, institutional repositories, not so