Currently, there are two main technology approaches for collecting Web analytics data: log-file analysis and page tagging.

Log-file analysis software reads the records, called log files, on the Web server, which record all clicks that take place on the server. Web servers have always stored all the clicks that take place in a log file, so the software interprets data that have always been available. A new line is written in a log file with each new request. For example, clicking on a link, an Ajax call, or submitting a form will each result in a new line being written.

Page tagging, on the other hand, sends information to a third-party server, where statistics can be generated. The browser executes JavaScript code that communicates with the tracking software, creating page tags.

Pixel tracking can be used to track e-mail campaigns. Here, a tiny, transparent pixel is placed in the e-mail. When you load the images in the e-mail, you will also load the tiny image that tracks your activity.

10.1 Log-file analysis

In terms of log-file analysis, you should know the following:

  • Log files are normally produced by Web servers, so the raw data are readily available. Page tagging, however, requires changes to the Web site.
  • Log files are very accurate—they record every click. Page tagging can be less accurate. If a user’s browser does not support JavaScript, for example, no information will be captured.
  • Log files are in a standard format, so it is possible to switch vendors and still be able to analyze historical data. Page tagging is proprietary to each vendor, so switching can mean losing historical data.
  • Log files record visits from search engine spiders—useful for search engine optimization.
  • Log files record failed requests, whereas page tagging only shows successful requests.

10.2 Page tagging

In terms of page tagging, you should know the following:

  • JavaScript makes it easier to capture more information (e.g., products purchased or screen size of a user’s browser). You can use log-file analysis to capture this information, but it will involve modifying the URLs (uniform resource locators).
  • Page tagging can report on events, such as interactions with a Flash movie, that log-file analysis cannot.
  • Page tagging can be used by companies that do not run their own Web servers.
  • Page tagging service providers usually offer a greater level of support. This is because it is a third-party service, whereas log-file analysis software is often managed in-house.

Because of the different methods of collecting data, the raw figures produced by the two services will differ. Sometimes, both are used to analyze a Web site. However, raw figures not matching up should not be a problem. It is through interpreting these figures that you will be able to understand how effective your online marketing efforts are.