The two main methods for tracking websites and monitoring site usage statistics are JavaScript page tagging and log file analysis.

Standard server-side web analytics is based on server logs. All HTTP requests and responses come into the server, and they are logged line by line. Log file analysis tools parse the log files and calculate the usage statistics of a website based on the values contained there.

Client-side tools, however, do not use server logs for data collection.  Instead, they use JavaScript page tagging and only record data when the page has successfully been loaded on a visitor’s browser. JavaScript page tagging involves adding a snippet of JavaScript code to each individual page of a website.

CardioLog uses the JavaScript page tagging method. For SharePoint portals and websites, the CardioLog JavaScript tracking code is automatically added to all page by activating the CardioLog Agent SharePoint Feature, thus making it possible to easily add and remove the CardioLog tracking agent without changing each page individually.

One methodology is not necessarily better than the other as there are advantages and disadvantages to both types of tracking systems.

The fact that each method uses different technology to collect data explains why the reported numbers tend to vary between them.

Some scenarios are only tracked with server-side tools:

1. Server-side tools can track information on automated search engine robot requests and other non-human visits, whereas JavaScript page tagging can’t detect non-human visitors at all.
2. Server-side tools can track information on failed page requests (error pages with HTTP status codes 401, 403, 404, 500 and redirects with HTTP status codes 301,302), whereas JavaScript page tagging only records a page if it was successfully viewed.
3. Server-side tools can track information on any device or browser that does not support JavaScript (some mobile devices, browsers with JavaScript switched off).

Some scenarios are only tracked with JavaScript page tagging and CardioLog:

1. CardioLog can collect extra client information on browser properties, page elements properties, operating systems, IP address, and even on interaction with Flash movies and other plug-in. It can also detect user interaction like a slight mouse movement or the press of a button. It is easier to add additional information to the JavaScript tag, which can then be collected by the CardioLog server. For example, information about the visitors' partial form completion, or the price of the goods they purchased, can be added in this way. With server-side log file analysis tools, information not normally collected by the web server can only be recorded by modifying the URL.
2. CardioLog tracks individual events that a visitor performs on a website, such as file downloads, clicks, form submissions, their path through the website, etc. This information can be used to help measure where a visitor drops-out of a complicated process, thus providing the business owners with the information that they need to make recommendations for simplification and improvement of that process.
3. With CardioLog, 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 up to one-third of all page views. Not counting cached pages seriously affects many metrics. It is for this reason server-side log analysis tools are not considered suitable for analysis of human activity on websites.

Log files are not 100% accurate. ISP page caching and proxies can twist data and consequently lead to inaccuracies.

JavaScript page tagging is not 100% accurate either, even though it is more accurate than log files. A certain percentage of people disable JavaScript in their browsers. DNS failures and other network issues can result in data not being captured where a log file would work well.

Intlock encourages each customer to perform his/her own load tests. Our customers have reported 99.7% accuracy.