Pros and Cons of 3rd Party Cookies for Web Analysts

PC CookiesIf you use the web you should by now be aware of “cookies,” those little bits of code that get placed on your computer that do everything from remembering your log in information on your favorite web site, to tracking every click you make. What many people don’t realize is, there are are two kinds of cookies: first party cookies and third party cookies. While both have an impact on Web Analytics, I will focus on the third party flavor today.

Third party cookies are basically set by a company/domain other than the one you are currently visiting. Usually they are set by an analytics tool, advertiser,  marketing firm or other third party that has some interest in tracking what you do on the site they placed cookies on. By default any site using an analytics tool is using third party cookies, unless the site owner/developer made a deliberate effort to use first party cookies instead.

Privacy advocates of course don’t like third party cookies for a variety of reasons – the most obvious being the tracking of what people do, especially by a third party you are not even aware of tracking you. Folks who are aware of this often take measures to block cookies, and most cookie blockers, anti-spyware and anti-spam programs block third party cookies more often than first party cookies – at a rate of around 10 – 15%.

Web analysts naturally should be alarmed by this – you can have as many as 10-15% of site visitors you cannot track if you use the default third party cookie that your analytics tool provides. However before jumping straight into using only first party cookies, keep the following in mind in regards to third party cookies:

  • If you have multiple web sites/domains and wish to track user behavior in aggregate, you can only do this with a 3rd party cookie (using a  separate first party cookie on each site and rolling up this data would cause some duplication of data as visitors overlap across the sites).
  • They make it easier to track what users do when they leave your site.
  • They make marketing campaigns easier to manage, especially if you host your landing pages on a different domain from your main site.

So an analysts, especially those working across multiple domains or on large online marketing campaigns, need to make a decision – accept the loss of 10-15% of tracking data, in order to gain more info on users across the domains they are tracking. For smaller sites, ones on a single domain, and ones who can incorporate all their campaigns on a single domain, can get away with using single-party cookies (and you can work with your analytics tool vendor to make this work).

Here’s just hoping that folks don’t start en mass blocking first party cookies in the near future.

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