First Party vs. Third Party Cookies and Their Importance in Web Analytics
As a Web Analytics consultant I am often asked what the relevance of using a 1st party cookie over a 3rd party cookie is. This question comes up when implementing web analytics solutions such as Omniture SiteCatalyst on a client’s web site. Part of the implementation process for Omniture in particular requires clients fill out a short “FPC” form (abbreviation for you guessed it, First Party Cookies) if the client wants to have the Omniture cookie set on their own domain instead of Omniture’s server. This is an optional process but is highly recommended by Omniture and myself as a consultant working on Omniture implementations. So it is part of my job to convince clients that using your own 1st party cookie is recommended over using Omniture’s default cookie (3rd party).
But what does this mean for the client? What are the implications of using a first party cookie over a third party cookie? Does it really make a difference? In short, yes. Generally I tell clients that 1st party cookies have higher acceptance rates than 3rd party cookies because of different browser cookie blocking settings, anti-spyware programs, etc. This is true, but it has always bothered me that I didn’t have any hard numbers to share with the client. I have “heard” through various sources that cookie acceptance rates can increase anywhere from 2% – 30% when using 1st party over 3rd party but I am not a fan of vagueness. So I decided to conduct my own test with various web sites. Some of the following data is from clients of mine or co-workers and some is from sites of friends or the companies they work for. All of it is actual data over the same time period but the sites remain anonymous for obvious reasons.
As you can see from the chart above, there is an average acceptance rate of around 98% when using your own first party cookie. When using Omniture’s default cookie (3rd party) the acceptance rate is only about 88% – 92%, a significant drop. Even using your own 3rd party cookie over Omniture’s gives a a significant boost with acceptance rates averaging around 95%. Why would you bother using your own 3rd party cookie and why is it accepted more than Omniture’s you ask? — With Omniture being a known web analytics provider, unfortunately their cookie domain is recognized and automatically blocked by some anti-spyware software programs.
How to check your own cookie acceptance rate if you are using Omniture
I often get clients that have already been using Omniture for years and unknowingly have been using Omniture’s default 3rd party cookie. In their defense, even if they are aware of both kinds of cookies they can often be mislead by a report within SiteCatalyst. If you go to Visitor Profile > Technology > Cookies within SiteCatalyst 14 you are NOT looking at a report showing the acceptance rate of your specific Omniture Visitor ID cookie…
This report is simply showing you what the acceptance rate of any 1st party cookie set on your own site would be based on the browser settings of your visitors. So if you are using Omniture’s 3rd party visitor ID cookie and you view this report, it is still showing you the acceptance rate of any general session based 1st party cookie set on your site NOT the acceptance rate of your persistent visitor ID cookie. What? Huh? — This can be confusing to many clients which is completely understandable. I was guilty of making this assumption myself in the past. To get the acceptance rate of your Omniture visitor ID cookie, whether it is being set on their server or yours, you have to take a few extra steps. First you go to one of your visitor reports under Site Metrics > Visitors > and choose one of the unique visitor reports (hourly, daily, monthly etc. depending on your date range). Then you have to filter that report by the “persistent cookies” link. Your report should look something like this at the top after you have made these selections:
After applying the filter you will notice a “Persistent Cookie Vis.” column, a “Non-persistent Cookie Vis.” column, and a “Total” column. To get your persistent cookie acceptance rate you simply divide the number of persistent cookie visitors by total visitors. If you are using Omniture’s default cookie (3rd party), you will likely see a significantly lower acceptance rate than what you see in the default “cookies” report under the “visitor profile” menu. Again, this is because the report under visitor profile is ALWAYS based on a 1st party session based cookie and the visitor report filtered by persistent cookies is ALWAYS based on your visitor ID cookie which could be your own 1st party cookie or Omniture’s default third party cookie depending on what was implemented for your site.
So in conclusion, yes – you should be setting your web analytics visitor cookie on your own domain whenever possible. Preferably this should be the same domain you are tracking visitors on (sub-domains are fine) whenever possible. If you have multiple domains and want to stick with one cookie instead of a separate cookie for each domain then just choose one of your own domains to host your visitor cookie. Even if it ends up being a 3rd party cookie on some of your sites you will still get a higher acceptance rate than Omniture’s default.
So what are you guys seeing? How do your persistent cookie acceptance rates compare to those posted here?
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11 Responses to “First Party vs. Third Party Cookies and Their Importance in Web Analytics”
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Al Dugan
Web Analytics Manager at Edgewater Technology with 12 years experience in online marketing specializing in search, affiliate, and web analytics. Startinga.com is my side project to share this experience with others of all skill levels from beginners to seasoned pros.
Great article!
[...] ShrimpTest will be doing) is at approximately 98% while third-party cookie acceptance drops to ~90% according to one study. 98% is pretty solid. Even then, we can take the remaining 2% of real users and collapse them by a [...]
For using a third party cookie, what are the steps required.
Do we need to set the Visitorid explicitly in the page code?
Hello Mausam,
To set up first party cookie tracking in Omniture you will need to contact Omniture support as they have a form you need to fill out and will provide you with the full instructions. The basic steps for Omniture are:
1) Fill out the form and submit to Omniture
2) Purchase an SSL certificate per Omniture’s instructions (if you have secure pages on your site)
3) Update a couple lines of code within your s_code.js file.
The whole process usually takes up to a few weeks as it depends on Omniture’s server update schedule.
Were you asking about Omniture or another platform?
Hi Al – Thanks so much for this article, it was really helpful! I’m working with a new client on their new(er) implementation and attempting to figure out if they’re using 1st party cookies. I’m thinking they are because the debugger seems to show it, but the acceptance rate is only at ~96.3% which is a bit lower than I expected. It’s a clothing ecommerce site, so I’m wondering if that impacts the acceptance. What are your thoughts?
Hi Elizabeth,
If you are using the Omniture debugger look at the first line to determine if they are using their own cookie (usually something like metrics.ClientDomain.com) or Omniture’s default server (usually something like 112.2o7.net). Remember it is possible to be setting your own cookie but as a 3rd party cookie. So if the domain you are questioning does not match the domain in that first line of the debugger then technically it is a 3rd party cookie (it is ok if the sub-domain is different but not the main domain).
In general I would not be worried with a 96% acceptance rate if there already is a 1st party cookie being used. If you determine you are using your own 3rd party cookie you could probably bump up that percentage a bit but in general a 3.7% nonacceptance rate for an e-commerce site is not bad at all.
Nevermind…I was off a decimal point. It’s a 99.6% acceptance
Oops just saw your reply — thank you for the help. I checked and it is metrics.ClientDomain.com and is set as a first party cookie. When, in your opinion, does the acceptance rate start becoming unreliable?
There really is no set number you should start to worry. It varies widely by industry. But in general, I have not seen many ecommerce sites under a 95% acceptance rate. However, smart phones are definitely starting to factor in and decrease overall percentages because for example the default on the iphone is to accept only 1st party cookies which is just another reason to always use a 1st party cookie whenever possible. Adobe NetAverages is a pretty cool site to check out if you are interested in overall trends in these kinds of things. It is still free for the next year or so.
We use 1st party cookies on one site, and the acceptance rate is 99.7%. On a site where we use 3rd party cookies, the acceptance rate is 91.1%.
My first thought when reading this is:
Why the hell dont they just give you the FPC to begin with. What benefit is there to implement the 3rd party cookie script?
And by the way, isnt it a “hidden” 3rd party cookie set by pointing the DNS to the Omniture tracking server?
Im curious!?