1. Hyperlinks in academia: some stylised facts and a first attempt at model development
by Franz Barjak, University of Applied Sciences Northwestern Switzerland

2. Why analyse hyperlinks in the academic web?
The web is an important communication channel in science.
99% of the respondents used internet browser software for research in a 2003 survey of 5 disciplines in 7 European countries (Barjak & Harabi, 2004)
Hyperlinks are to a large percentage related to scholarly activity (Bar-Ilan, 2004; Wilkinson, Harries, Thelwall, & Price, 2003). Hyperlinks are created to point to
information on the web (information-related),
because of the characteristics of organisations or individuals which own or create the linked-to web documents (owner-related)
or because of characteristics of the environment in which the links are created (environment-related).
Hyperlinks are to a large percentage related to scholarly activity
research-related: UK 27%, Israel 20%
education-related: UK 27%, Israel 9%
UK: Libraries and e-journals 21%, similar departments 7%
Israel: professional (work-related): 31%
Franz Barjak, Institute for Interdisciplinary Economic and Social Research
07/12/2018

3. Outlinks are less suitable for analysis for technical reasons
S&T indicators: Hyperlinks can be used to construct complementary indicators for analysing and steering science & technology (Thelwall, 2004)
Inlinks are similar to citations from the perspective of the cited author and outlinks from the perspective of the citer
Inlinks can be considered as a proxy to web impact (Thelwall & Harries, 2004)
Inlinks can function as indicators on processes and structures in S&T outside of internet use and the web
Outlinks are less suitable for analysis for technical reasons
The quality of link data is reduced notably by “noise” or anomalies (Thelwall, 2003; Thelwall, 2004; Thelwall & Harries, 2004)
The role of hyperlinks:
inlinks are similar to citations from the perspective of the cited author and outlinks from the perspective of the citer; the first is more meaningful in scientometrics than the second, as citations are an indicator for the impact of a publication
Inlinks can be considered as a proxy to web impact (Thelwall & Harries, 2004): web impact denotes the perception, visibility or significance of a web document (and/or its owner) by other internet users (scientists, non-scientists)
outlinks are less suitable for technical reasons
are on one site only and maybe subject to crawler coverage problems (Thelwall, 2004)
are under the control of the site owners and created by them (Thelwall, 2004)
less researched (see e.g. Thelwall 2003)
Hyperlinks contain information on other processes outside of the internet, e.g.
information exchange and communication relations in science
the structure of science networks
or the significance of web presences and/or the scientific knowledge included on them to
industry,
the health sector,
public administration or
the society in general
The problem of noise or anomalies indicates, that large data sets or highly aggregated datasets are necessary to identify the meaning of the data and/or that the data ghas to be cleaned as good as possible. Such noise is for instance:
Automated links created by web page authoring software
Interlinked web databases
Sites hosted for other organizations (“mirror sites”)
Links without meaning
Franz Barjak, Institute for Interdisciplinary Economic and Social Research
07/12/2018

4. What do we know about the relationship between links and scholarly activity? Information-related factors
The more information is included in a web document, the more links point to it (Barjak & Thelwall, 2006; Li, Thelwall, Wilkinson, & Musgrove, 2005; Thelwall & Harries, 2004)
The higher the quality (e.g. usefulness, credibility) of information in a web document, the more links point to it (Barjak, Li, & Thelwall, in press; Fogg et al., 2001; Liu, 2004; Park, Barnett, & Nam, 2002).
Quality is not an absolute measure but relative, depending for instance on the timeliness of the information (Beaulieu & Simakova, 2006) or the availability of information on other sites.
The longer a web presence has been running under the same URL, the more inlinks it receives (preferential attachment).
Quality:
web documents with full text articles receive more inlinks than web documents without (Barjak, Li, & Thelwall, in press)
(Park, Barnett, & Nam, 2002) used not data on the academic web, but the 152 most visited Korean websites in August 2000
Franz Barjak, Institute for Interdisciplinary Economic and Social Research
07/12/2018

5. Influence of the type of homepage content on external inlinks
All models clearly show that the existence of full text or hyperlinks pointing to full text (PDF-variable) significantly increases internal and external inlink counts. For external links there also seems to be a negative effect of biographies (BIOGR) and a positive effect of project descriptions (PROJECT). However, it seems unlikely that biographies on homepages deter inlinks, but perhaps a biography alone is not sufficiently interesting to cause somebody to link to a page.
Source: Barjak, Li & Thelwall, in press
Franz Barjak, Institute for Interdisciplinary Economic and Social Research
07/12/2018

6. Q Quantity and quality of information on web documents
Number of inlinks +
Franz Barjak, Institute for Interdisciplinary Economic and Social Research
07/12/2018

7. Owner-related factors
7. The higher the peer recognition/rating of the page-owner, the higher the number of links to their web documents:
at the level of universities (Smith & Thelwall, 2002, 2005; Thelwall, 2001, 2002a; Thelwall & Harries, 2003, 2004; Thelwall & Wilkinson, 2003)
and departments (Chen, Newman, Newman, & Rada, 1998; Fry, 2006; Li, Thelwall, Musgrove, & Wilkinson, 2003; Li, Thelwall, Wilkinson, & Musgrove, 2005)
but rather not at lower levels: research teams (Barjak & Thelwall, 2006), individual scientists (Barjak, Li, & Thelwall, in press).
The higher the impact of the work of the page-owner (departmental level), the higher the number of links to their web documents (Li, Thelwall, Wilkinson, & Musgrove, 2005; Tang & Thelwall, 2003).
9. Higher rated scholars do not produce web content with a higher impact, but they produce more content (Thelwall & Harries, 2004).
7. c) E.g. no relationship for productivity measures and links to the web pages of research teams (Barjak & Thelwall, 2006)
Franz Barjak, Institute for Interdisciplinary Economic and Social Research
07/12/2018

8. P/I/R Productivity, impact and recognition of web document owner
Number of inlinks +
Q Quantity and quality of information on web documents
Franz Barjak, Institute for Interdisciplinary Economic and Social Research
07/12/2018

9. 10. Only few hyperlinks represent communication or collaboration relations between the owners (Bar-Ilan, 2004; Beaulieu & Simakova, 2006; Fry, 2006; Heimeriks, Hörlesberger, & Van den Besselaar, 2003; Thelwall, 2003; Wilkinson , Harries, Thelwall, & Price, 2003). 11. No clear relationship between the amount of collaboration activities and inlinks to the web presences is visible (Barjak, Li, & Thelwall, in press; Barjak & Thelwall, 2006; Heimeriks & Van den Besselaar, 2004). 12. An influence of demographic characteristics of the page owners on inlinks is not confirmed (Barjak, Li, & Thelwall, in press; Barjak & Thelwall, 2006; Thelwall, Barjak, & Kretschmer, in press).
Demographic characteristics:
gender effect on inlinks: yes (Barjak, Li, & Thelwall, in press)
no (Barjak & Thelwall, 2006; Thelwall, Barjak, & Kretschmer, in press)
age effect (Barjak, Li, & Thelwall, in press; Barjak & Thelwall, 2006).
Franz Barjak, Institute for Interdisciplinary Economic and Social Research
07/12/2018

10. P/I/R Productivity, impact and recognition of web document owner
Number of inlinks +
Q Quantity and quality of information on web documents
C Collaboration and communication of web document owner
D Demographic char. (older, female) of web document owner -
Resources
-/+
Collaboration and communication of web document owner:
Collaboration is positively related to research productivity and impact (several times confirmed, see e.g. the survey in Katz & Martin, 1997)
Demographic characteristics
older scientists use the web less often than younger scientists (Barjak, 2006)
Female scientists have structurally weaker positions than males (fewer professors, fewer heads of departments etc.) and fewer resources  fewer „means of knowledge production“  fewer information on the internet  fewer inlinks
Franz Barjak, Institute for Interdisciplinary Economic and Social Research
07/12/2018

11. Mean internal and external inlinks by discipline
Chemistry and psychology have lowest link numbers, computer science has the highest link number, economics and astroomy are in between
Internal and external link numbers are very similar again
Source: Barjak, Li & Thelwall, in press
Franz Barjak, Institute for Interdisciplinary Economic and Social Research
07/12/2018

12. Mean internal and external inlinks by country
Internal and external link numbers are similar except for CH
UK, CH, DE and DK are at the same level, IT and IR have somewhat smaller link numbers
Source: Barjak, Li & Thelwall, in press
Franz Barjak, Institute for Interdisciplinary Economic and Social Research
07/12/2018

13. Environment-related factors
13. The number of links differs between scientific disciplines and research fields (Barjak, Li, & Thelwall, in press; Li, Thelwall, Wilkinson, & Musgrove, 2005; Nelson, 2005; Tang & Thelwall, 2003, 2004; Thelwall, Harries, & Wilkinson, 2003; Thelwall, Vaughan, Cothey, Li, & Smith, 2003).
14. The link patterns (e.g. sources of inlinks) differ between disciplines (Harries, Wilkinson, Price, Fairclough, & Thelwall, 2004; Thelwall, 2004).
15. The number of links differs between countries (Barjak, Li, & Thelwall, in press; Barjak & Thelwall, 2006; Li, Thelwall, Wilkinson, & Musgrove, 2005; Thelwall, Vaughan, Cothey, Li, & Smith, 2003).
The larger the distance between two universities the fewer the number of links that connects them (Heimeriks & Besselaar, 2006; Thelwall, 2002b, 2002c).
Link patterns:
links from link lists (sociology)
links from peers‘ homepages
links from outside of science, firms etc.
Franz Barjak, Institute for Interdisciplinary Economic and Social Research
07/12/2018

14. P/I/R Productivity, impact and recognition of web document owner
Number of inlinks +
Q Quantity and quality of information on web documents
Distance
C Collaboration and communication of web document owner -
D Demographic char. (older, female) of web document owner
Resources
-/+
E Environmental issues (discipline/field, organisation, country, time)
Distance has a negative effect on the frequency and intensity of R&D collaboration (e.g. Thomas Allen in 1977)
Environmental issues
Disciplines with many links: Computer Science (Mathematics, Linguistics, Library and Information Management, Physics, Astronomy)
Disciplines with few links: Philosophy, (Chemistry, Humanities, Social Sciences except for Economics)
 country differences between subjects (Thelwall, 2004)
Explanations:
 communication practices, internet use of disciplines/fields/countries (Kling & McKim, 2000) Fry 2004: mutual dependence and task uncertainty
 size of disciplines/fields/countries
Franz Barjak, Institute for Interdisciplinary Economic and Social Research
07/12/2018

15. Further research needs
P/I/R: Is there a relationship (causality) between productivity/impact/ recognition and inlinks that is independent of the larger size of the web documents?
C: Collaboration and communication
Are collaboration and communication related to the size of web presences?
Are collaboration and communication related to the number of inlinks?
Improvement of concept operationalisation:
time lags,
different types of research output,
collaboration & communication outside of research
Do collaboration and communication have an effect on inlinks?
Operationalisation too much research-oriented: not only research c&c, but c&c in general, e.g. including joint infrastructure use, funding relationships, technology transfer, membership to organisations & committees, teaching etc.
Franz Barjak, Institute for Interdisciplinary Economic and Social Research
07/12/2018