The two common types of data collection (The 2 main types of approached to collect Web Analytics data):

• Logfile Analysis
• Page Tagging
• Other data collection methods
• Logfile Analysis Vs Page Tagging

Logfile Analysis

A server log is a log file (or several files) automatically created and maintained by a server of activity performed by it. Example: History or visits data collected in log files including date or time of visit, ip address, referrer etc.

Servder log files are accessable only to one who has access to the server place where log files are stored. It’s cannot be accessed by general internet users.

A statistical analysis of the server log may be used to examine traffic patterns by time of day, day of week, referrer, or user agent. Efficient web site administration, adequate hosting resources and the fine tuning of sales efforts can be aided by analysis of the web server logs.

Logfiles refer to data collected by your web server, which is independent of a visitors’ browser. By default, all requests to a web server (pages, images, pdf’s etc) are logged to a file – usually in plain text. This type of technique is known as server-side data collection.

Logfile analysis was historically the way to analyse web site visitor behaviour. Web server logfiles are readily available, hence site owners simply purchased the software to analyse their logfiles.

Logfile analysis is almost always performed in-house.

Logfile analysis typically involves a one-off software purchase; however, some vendors are introducing maximum annual page views with additional costs to process additional information.

Page Tagging

Page tags uses JavaScript on each page to notify a third-party server when a page is rendered by a web browser.

Page Tags refer to data collected by a visitors’ web browser, achieved by placing code on each page of your site. Often it is simply a single snippet (tag) of code referencing a separate javascript file – hence the name. Some vendors also add multiple custom tags to set/collect further data. This type of technique is known as client-side data collection.

Page tagging can be performed in-house, but it is more often provided as a third-party service.
Page tagging most often involves a monthly fee, although some vendors offer installable page tagging solutions with no additional page view costs.

The web analytics service also manages the process of assigning a cookie to the user, which can uniquely identify them during their visit and in subsequent visits.

Other data collection methods

HYBRID method. That is, combining both web logs with page tags.

Network Data Collection devices or “packet sniffers” gather web traffic data from routers into ‘black box’ appliances. Possibly because of implementation complexities/cost, only a couple of vendors are known to use the NDC method.

Web server API/Loadable Module (also known as a plugin, though not strictly correct). These are programs that extend the capabilities of the web server. For example, enhancing and/or extending the fields that are logged. Typically the collected data is then ’streamed’ to a reporting server in real time.

Difference between Page Tags Analysis and Logfiles Analysis

Page Tagging

Advantages:
• Gets through proxy/caching servers - Therefore more accurate session tracking
• Provides web design parameters - Do your visitors have Flash, what are their screen resolution, what version of javascript do they have?
• Track client side events - Javascript, Flash and web v2.0 events
• Capture eCommerce data easily client-side - Often web sites use a third party to process card data
• Data can be collected/processed in near real-time

Disadvantages:
• Setup errors = loss of data -If you make a mistake with your tags, data is lost and you can not go back and re-analyse
• Firewalls – can mangle or restrict tags
• Can not track bandwidth or completed downloads - Tags are set when the page/file is requested not when the download is complete
• Can not track SE spiders as robots ignore page tags

Logfile Analysis

Advantages:
• Historical data can be reprocessed easily
• No Firewall issues to worry about
• Can track bandwidth and completed downloads - differentiate completed and partial downloads
• Can track search engine spiders/robots
• Can track mobile visitors

Disadvantages:
• Proxy/caching inaccuracies If a page is cached, no record is logged on your web server
• No web design parameters
• No event tracking (javascript, Flash, web v2.0)