Archive for May 22nd, 2008

Log Files vs Javascript Code

Thursday, May 22nd, 2008

I have written in the past about the various mechanics of click fraud software on the market, but I thought I would extend on this and talk about the benefits of log file analysis versus javascript tag implementations.

If you have checked out my consultancy page, you will see I am a fan of log file analaysis, in this post I will say why I hold this position, and it is due to two incredibly important facts

You can Disable javascript on your browser

Users have the option to disable javascript on their browser. As JS is client side scripting language, if the browser is not prepared to run your script, there is no way to capture metrics on the visit. Any tech-savvie click fraudster will disable javascript as their first port of call. This then renders your click fraud tool useless.

Some bots can be in and out before a script is loaded.

Analysis of certain click bots has shown that they can hit your site, register a click with Google and drop off your site, before your javascript has had time to load up and capture the visit details. This visit will however be recorded in your web servers log files.

How to Test This

Don’t belive me, then here is a quick test in another area of log file vs javascript to prove the problems with scripted implementations.

1) Review your traffic data from a log file analysis package such as webalizer

2) Review your traffic data from a javascript service such as Google analytics.

I am prepared to bet that your visits will be higher on the log file to javascript package. This is due to a number of factors including the two outlined above.

As a parting word I would like to say that there are some instances where javascript tags are the only way to analyse your traffic, for example if your ISP does not give you access to your logs in a hosted environment. If that is the case, go with the scripts, the more evidence you have, the better your chance of a refund from the search engines.

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