There are two primary types — page tagging (otherwise known as client-side data collection) and log file analyzers.

Page Tagging

Page tagging collects data via a visitor’s web browser. It is typically JavaScript code implemented on every page of a website — this is where the term “page tagging” comes from. This method is mostly used by outsourced hosted vendors like Google Analytics. Here is a short list of benefits versus disadvantages.

Benefits of Page Tagging:

• Provides more accurate session tracking.
• Allows data collecting and storage for later analysis by your hosted vendor.
• Tracks client-side events.
• Captures client-side e-commerce data.
• Data stored, created and organized for you by the hosted software.
• Needs less IT time to implement and manage.

Disadvantages of Page Tagging:

• Inaccuracies setting up and tagging your site pages result in inaccurate data collected.
• Cannot track completed, partial, or abandoned downloads.
• Firewalls can skew data.
• Latency can result in untracked visitors.
• Deleted or rejected cookies can cause inaccurate tracking.

Log File Analyzers

Log file analyzers, otherwise known as server-side data collectors, are independent of web browsers and collect data as it is requested from the website’s server. Log file analyzers are typically used by standalone software vendors and take a lot more resources to maintain. Here is a short list of benefits versus disadvantages.

Benefits of Log File Analysis:

• No firewall issues.
• Can track completed downloads.
• Tracks mobile visitors by default.
• Can apply filters retroactivley.

Disadvantages of Log File Analysis:

• No event tracking.
• All program updates must be completed by your own team.
• Robots multiply visitor count, resulting in skewed data.
• Large amount of disk space needed to store history.
• IT department needs to manage, update, and monitor system.
• One IP address registers one person.
• Cached pages are not counted.

Looking at both these popular data-collecting methods, it is clear that where one system fails, the other exceeds. One reason I like using Google Analytics over other systems is that it is versatile. For example, if I wanted to use both data-collecting methods, I could configure the Urchin log file analyzer and Google Analytics simultaneously in order to get the best of both worlds. A reason I might do this is if I wanted to track activity behind a firewall like a local intranet against what is happening on my client side of my customer’s website.

Note: Urchin is a downloadable software system that Google Analytics purchased in April 2005, which has many more benefits than most other log file analyzers. You can download it here: www.google.com/urchin/download.html.

It is important to note that there are several thorny issues with data collection no matter what software or method you choose. Understanding that your data will ultimately not be 100% accurate is the start to truly understanding and interpreting your data and ultimately making the appropriate marketing decisions based on it.

Web Analytics with JavaScript Page Tagging and  Server Log Files : Comparison of 2 Analytical Methods