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Inf@Vis!

The digital magazine of InfoVis.net

Web Traffic
by Juan C. Dürsteler [message nº 66]

Last Week we reached the conclusion that pure logfile analysis is insufficient in order to know what happens inside our web site. Today we'll see some of the visualisation proposals to overcome this problem.

In order to do this we'll follow the scheme that Stephen G. Eick of Visual Insights depicts in his suggestive article "Visualizing Online Activity" (Communications of the ACM, August 2001; available at ACM digital library under subscription). 

According to Eick, there are three areas where information visualisation can help us to understand our visitor's activity:

  1. Visualisation of the structure of the web site. It serves as a clarifying element for the site creators and, as sitemap, it is a navigational element for the end users.

  2. Revelation of the fluxes and individual paths of the visitors. This makes it possible to create a more effective web site, avoiding "dead pages" and bottlenecks.

  3. Monitoring the site's real time activity. Helping the web site operators to improve the yields of the business thanks to the knowledge of what is being purchased, what pages are "hot", etc.

We already spoke about section 1 in the past issues 47 and 48 of the e-zine but it's still worth remembering the existence of systems based on hyperbolic geometry to represent the structure of large web sites. Among them those provided by Inxight or Silicon Graphics Site Manager that uses the technology developed by Tamara Munzner as part of her PhD thesis.

StarTreeInxight.gif (31903 bytes) MunznerH3.gif (68124 bytes)
StarTree from Inxight Software is a system that represents the web site structure using 2D hyperbolic geometry. 
(Click on the image to see a zoom of it).
The work of Tamara Munzner on 3D hyperbolic space representation of the Web. See the article o the H3 system.
(Click on the image to see a zoom of it).

So we'll concentrate in this issue on the visualisation of visitor's flow and individual paths. The goal of this type of tool is the analysis of the entry points of our visitors, what pages they visit and where they leave the web. Path analysis concentrates on what individual users do within the web site, while flow analysis integrates the paths and statistics of many users in order to reveal the global usage patterns of the site as a whole.

Examples of path analysis can be found at Advanced Log Analyzer from Vasin Knoware. This analyser allows you to visualise the individual paths of the last 30 visitors or an aggregate of the most frequent paths among many other statistics. In both cases the visualisation is made in a tabular style.

Sawmill offers a visualisation of individual paths à la Windows Explorer that is quite clear and occupies less space than the previous case. 

SawMillPath.gif (25454 bytes) AdvancedLogAnalyzer.gif (20401 bytes)
SawMill. Visualization of individual paths using a tree scheme similar to that of the Windows Explorer. It's very clear and interactive.
(Click on the image to see a zoom of it).
Advanced Log Analyzer. Analysis in tabular form of the last 30 visitors' paths.
(Click on the image to see a zoom of it).

A much more attractive visual system is the one that VISVIP providesl, developed by John Cugini as part of the interesting set of tools WebMetrics from the NIST. VISVIP represents the structure of the web site as a 2D graph over which the path of a particular user is superimposed as a smoothly curved line that jumps from page to page. Several arrows included in the line show the direction and dotted lines proportional in length to the time spent are placed in each visited page.

VisVip2.gif (22006 bytes)
VISVIP. Created by John Cugini, is part of the set of tools called WebMetrics that is available at NIST. 
It represents the path using a smooth curve that shows that trajectory and direction of the movement as well as the time spent in each page.
(Click on the image to see it zoomed.)
EbizInsights. Shows the visitor's flow between pages. Each rectangles is a page. The one in the center is the page of our interest. On both sides are shown the pages where visitors have come from (left) and the ones where the users have left (right). Each page contains statistical information. It's part of VisualInsights solutions 

As an example of flow analysers, Eick himself proposes the graphical tools of their own solution called Ebizinsights, software devoted to the e-business sites that represents data in several graphical forms (see the Gallery at Visual Insights site). 

In this case the flow between pages is represented by a rectangle (the page in focus) with lines that link it to the pages where the users have come from and with other pages where the users have left. Each page contains the percentage of visitors coming in or going out. Clicking on a particular page, it becomes the centre and shows all the pages where users come and go.

Next week we'll continue exploring visualisations of visitor behaviour within a web site.


Links of this issue:

http://www.infovis.net/printMag.php?num=65&lang=2  
http://www.visualinsights.com  
http://portal.acm.org/portal.cfm  
http://www.infovis.net/printMag.php?num=47&lang=2  
http://www.infovis.net/printMag.php?num=48&lang=2  
http://www.inxight.com  
http://www.sgi.com/software/sitemgr.html  
http://graphics.stanford.edu/~munzner/  
http://www-graphics.stanford.edu/papers/h3/  
http://www.vknoware.com/ala/  
http://www.vknoware.com/ala/sample/vis_paths.htm  
http://www.vknoware.com/ala/sample/common_paths.htm  
http://www.flowerfire.com/sawmill/  
http://www.itl.nist.gov/iaui/vvrg/cugini/webmet/visvip/vv-home.html  
http://zing.ncsl.nist.gov/WebTools/  
http://www.itl.nist.gov/iaui/vvrg/staff/john.html  
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