Usage Statistics For Web Sites
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Information on performance indicators for Web sites has been published elsewhere [1] [2]. This document provides additional information on the specific need for usage statistics for Web sites and provides guidance on ways of ensuring the usage statistics can be comparable across Web sites.
When a user accesses a Web page several resources will normally be downloaded to the user (the HTML file, any embedded images, external style sheet and JavaScript files, etc.). The Web server will keep a record of this, including the names of the files requested and the date and time, together with some information about the user's environment (e.g. type of browser being used).
Web usage analysis software can then be used to provide overall statistics on usage of the Web site. As well as giving an indication of the overall usage of a Web site, information can be provided on the most popular pages, the most popular entry points, etc.
Usage statistics can be used to give an indication of the popularity of Web resources. Usage statistics can be useful if identifying successes or failures in dissemination strategies or in the usability of a Web site.
Usage statistics can also be useful to system administrators who may be able to use the information (and associated trends) in capacity planning for server hardware and network bandwidth.
Aggregation of usage statistics across a community can also be useful in profiling the impact of Web services within the community.
Although Web site usage statistics can be useful in a number of areas, it is important to be aware of the limitations of usage statistics. Although initially it may seem that such statistics should be objective and unambiguous, in reality this is not the case.
Some of the limitations of usage statistics include:
Although Web site usage statistics cannot be guaranteed to provide a clear and unambiguous summary of Web site usage, this does not mean that the data should not be collected and used. There are parallels with TV viewing figures which are affected by factors such as video recording. Despite such known limitations, this data is collected and used in determining advertising rates.
The following advice may be useful:
You should ensure that you document the approaches taken (e.g. details of the analysis tool used) and any processing carried out on the data (e.g. removing robot traffic or access from within the organisation). Ideally you will make any changes to the processing, but if you do you should document this.
Traditional analysis packages process server log files. An alternative approach is to make use of an externally-hosted usage analysis service. These services function by providing a small graphical image (which may be invisible) which is embedded on pages on your Web site. Accessing a page causes the graphic and associated JavaScript code, which is hosted by a commercial company, to be retrieved. Since the graphic is configured to be non-cachable, the usage data should be more reliable. In addition the JavaScript code can allow additional data to be provided, such as additional information about the end users PC environment.
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Web page by Brian Kelly of UKOLN.
Last Modified 24-October-2005
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