We all know that we should be using web analytics to analyze website visitor behavior and online marketing channel performance. However, what kind of web analytics should we use? Should you opt for log file analysis or page tagging or a bit of both? First, let’s define what we mean by these terms.
Page tagging involves placing a piece of code, usually externalized JavaScript, on each page of your site and is sometimes called client-side data collection. Every time a visitor’s browser opens a tagged page, the script is processed and the visitor’s information is collected. Log file analysis refers to data collected by your web server. What is the difference from the point of view of web analysis?
The bad news is that both strategies have their pros and cons, so here it goes.
Labeling benefits page
o Because the data is collected on the client side, this fixes any proxy and caching issues
o It will give you information about web design parameters such as browser versions, platform versions, screen resolution, connection speed, etc.
o Client-side event tracking, such as JavaScript and flash events
Disadvantages tagging page
o Firewalls may prevent or interfere with the processing of scripts
o Configure costs associated with code insertion.
o Inserting code can lead to errors
o Will not detect page errors like 404
o Because the robots ignore the scripts they cannot crawl the search engine spiders
o Cannot directly crawl non-html pages
o Provider specific
Advantages of log file analysis
o Historical data can be analyzed
o Low installation cost
o No firewall issues
o Easily track page errors
o You can crawl search engine spiders
or Independent Provider
o Can crawl non-html pages such as PDF files
Disadvantages of the log file
o Proxy/caching inaccuracies. If a page is cached, no log is recorded on your web server
o No web design parameters
o No event tracking
If you’re used to looking at web statistics using Web Trends, for example, you might notice significant differences in the number of visitors. By moving to log file analysis, the number of visitors can increase by 20-30%. If your site does not use persistent cookies, your web analytics program cannot identify unique visitors, therefore all visitors are aggregated as a total. Typically, unique visitors make up 20-30% of total website visits, so this metric will be inflated by this amount. Sometimes you will see a dramatic reduction in visits to the site. This is usually because web analytics programs remove the loading of graphics that other programs mistakenly count as visits.
Other differences in visitor numbers are generally due to how programs define a visit. A visit duration of 30 minutes means that multiple visits from the same IP address within this time period will be counted as one visit. Change this parameter to 15 minutes and these visits could be counted multiple times and your total visits will increase. Finally, when a web browser loads a PDF file, it brings up different parts of the file at different times, and some programs may count this as multiple requests for the same file. A good web analytics program will collapse these multiple downloads into one.
It’s important to understand these differences and manage your peers’ expectations, as surprise drops in website metrics can sometimes lead to disappointment with measuring website performance altogether.
For more information on web analytics, please contact us at http://www.ju2.com and keep an eye on our blog at http://www.ju2analytics.com