9 Logging Usage

Usage data can be generated in a number of ways, with two common approaches:

  • Log file analysis, which reads log files containing web server transaction records

  • Page tagging, which uses JavaScript to notify a third-party server when a page is rendered by a web browser.

Each of these approaches has advantages and disadvantages, summarized below.

9.1 Log File Analysis

Advantages of log file analysis over page tagging include:

  • Web servers normally produce log files, so the raw data are already available. No changes to the website are required.

  • The data is on the organization’s own servers in a standard rather than proprietary format. This makes it easy for an organization to switch analysis programs later, use several different programs, and analyze historical data with a new program.

  • Log files contain information on visits from search engine spiders. Although these MUST NOT be reported as part of user activity, it is useful information for search engine optimization.

  • Log files require no additional DNS lookups. Thus, there are no external server calls which can slow page load speeds or result in uncounted page views.

  • The web server reliably records every transaction it makes, including items such as content generated by scripts, and does not rely on the visitor’s browser.

9.2 Page Tagging

The main advantages of page tagging over log file analysis are:

  • Counting is activated by opening the page, not requesting it from the server. If a page is cached it will not be counted by the server. Cached pages can account for a significant proportion of page views.

  • Data is gathered via a component (tag) in the page, usually written in JavaScript, in conjunction with a server backend to manipulate and store the data in a database allowing complete control over how the data is represented.

  • The script may have access to additional information on the web client user that was not sent in the query.

  • Page tagging can report on events that do not involve a request to the web server.

  • Page tagging is available to companies who do not have access to their own web servers.

  • The page-tagging service manages the process of assigning cookies to visitors; with log file analysis, the server must be configured to do this.

  • Log file analysis is almost always performed in-house. Page tagging can be done in-house but is more often provided as a third-party service. The cost differences between these two models can also be a consideration.