The document discusses how Google Analytics uses cookies to track user behavior across websites. It explains the purpose and expiration times of the main Google Analytics cookies like _utma, _utmb, and _utmz. It also covers how to test if cookies are working properly, how to implement cross-domain tracking, and how to customize cookie settings. Ensuring cookies are functioning correctly is important for accurate traffic source data and visitor tracking in Google Analytics.

1. Crunching Cookies without
Dropping Crumbs
By Nikki Rae
@analyticsgirl

2. Nikki Rae
• Managing Director Future Insight Analytics
Ltd.
• Google Analytics Specialist
• First #brightonseo – 19th Feb 2010!!
• @analyticsgirl

3. Todays Session
• What is a Cookie?
• How can you tell if they are working properly?
• What happens if they aren't working?
• What is their role in cross domain tracking?

4. Why Do I Need to Know this?
– Many SEOs only view the Keyword report to
look at
• Visits to Keywords
• Bounce Rate to Keywords
– How can I track keywords across sites?
– How can I make sure my tracking is
working?

5. What is a Cookie?
• Cookies are used to help Google Analytics
‘remember’ what a user has done and how
they have interacted with a website.

6. Ga.js Cookie Usage
• Which domain is being used?
– Sub Domains?
– Multiple Domains?
• Who is using the site?
• How many times have they visited the site?
• How did they get to the site?
• When did a visit start/end?
• Maintain visitor level custom variable
information

7. Google Analytics Cookies
• 5 Main Cookies
– _utma
– _utmb
– _utmc
– _utmz
– _utmv

8. Visitor Cookie
__utma Expires 2 years from Unique Site Visitor
set/update
1. If Cookie does not
exist
a. Must be first
visit
b. Cookie is set
2. If cookie exists
a. Must be
return visit
b. Cookie is
updated
every time
data is sent
to GA

9. Session Cookies
__utmb Expires 30 mins from Sessions/ Visits
set/update
1. If Cookie does not
exist
a. Must be a
new
session/visit
b. Cookie is set
2. If cookie exists
a. Must be
current visit
b. Cookie is
updated
every time
data is sent
to GA

10. Session Cookies
_utmc Expires End of Not used in ga.js.
Browser Session

11. Campaign Cookie
__utmz Expires 6 Traffic Source
months from
1. Source
set/update
2. Medium
3. Campaign
Name
4. Campaign
Term
Cookie is
updated every
time data is
sent to GA

12. Custom Variable Cookie
__utmv 2 years from Visitor Level
set/update Custom Variable
1. Need to use
_setCustomVar
method
Cookie is updated
every time data is
sent to GA

13. Cookies Failing?
• Pages not tracked
• Traffic Sources/Mediums etc. incorrectly
recorded e.g. PPC traffic showing as organic
• Cookies are device and browser based
– One unique visitor per browser per device
– Can misrepresent reality

14. Testing Tracking
• Download - https://chrome.google.com/webstore/detail/google-analytics-
debugger/jnkmfdileelhofjcijamephohjechhna

15. Switch Debugger ON
• Switch it ON

16. Find Advanced Settings
• Click ‘Show Advanced Settings’

17. Click ‘Clear Browsing Data’
• Click ‘Clear Browsing Data’

18. Delete Cookies
• Delete Cookies from ‘beginning of time’

19. Go to your Site
• Go to your site via any medium
• Select CTRL-SHIFT-J
• This is the information that would be sent to Google Analytics

20. For Example…
• If you entered your site via a PPC Ad, and the
following data appeared, you’d know it was
not correctly tracked
• Most likely, not using auto-tagging or GA
Manual Tagging

21. Gif Request Parameters

22. GA Debug.js

23. Viewing Cookies
• Back to ‘Advanced Settings’

24. Content Settings
• Then click ‘Content Settings’

25. All Cookies an Site Data
• Click ‘All Cookies and Site Data’

26. Google Analytics Cookies

27. Identifying Unique Visitors
_utma 209459845.1349019670.1365484756.1365484756.1365484756.1
1. Domain hash, unique for each domain
209459845.1349019670.1365484756.1365484756.1365484756.1
2. Unique Identifier
209459845.1349019670.1365484756.1365484756.1365484756.1
3. Timestamp for first time you visited the site
209459845.1349019670.1365484756.1365484756.1365484756.1
4. Timestamp for previous visit
209459845.1349019670.1365484756.1365484756.1365484756.1
5. Timestamp for start of current visit
209459845.1349019670.1365484756.1365484756.1365484756.1
6. Number of sessions
209459845.1349019670.1365484756.1365484756.1365484756.1

28. First Session
In last example, the Timestamp for
• 1st visit (1365484756)
• Previous Visit (1365484756)
• Current Visit (1365484756)
Are all the same as this is the first and only visit (number
of sessions=1)
The combination of Unique ID and timestamp of first visit
form a unique identifier that Google Analytics uses to
identify different visitors.

29. Session Identifiers
_utmb 209459845.5.10.1365484756
_utmc 209459845
1. Domain hash, unique for each domain
209459845.5.10.1365484756
2. Number of Pageviews in current session
209459845.5.10.1365484756
3. The 10 in the UTMB cookie starts at 10 on every site.
And each time you click on an outgoing link it will
count down until it reaches 0.
It’s part of some outgoing links tracking system in the ga.js
that never appeared in the GA interface (Andre Scholten)
209459845.5.10.1365484756
4. Timestamp for current session
209459845.5.10.1365484756

30. Campaign Identifiers

31. Campaign Identifiers
_utmz 209459845.1365484756.1.1.utmcsr=google|utmccn=(organic)|utmcmd=organic|utmctr=(not%20provided)
1. Domain hash, unique for each domain
209459845.1365484756.1.1.utmcsr=google|utmccn=(organic)|utmcmd=organic|utmctr=(not%20provided)
2. Timestamp when cookie was set
209459845.1365484756.1.1.utmcsr=google|utmccn=(organic)|utmcmd=organic|utmctr=(not%20provided)
3. Session Number
209459845.1365484756.1.1.utmcsr=google|utmccn=(organic)|utmcmd=organic|utmctr=(not%20provided)
4. Campaign Number – Number of different campaigns used to enter site
209459845.1365484756.1.1.utmcsr=google|utmccn=(organic)|utmcmd=organic|utmctr=(not%20provided)
5. Campaign Source
209459845.1365484756.1.1.utmcsr=google|utmccn=(organic)|utmcmd=organic|utmctr=(not%20provided)
6. Campaign Name
209459845.1365484756.1.1.utmcsr=google|utmccn=(organic)|utmcmd=organic|utmctr=(not%20provided)
7. Campaign Medium
209459845.1365484756.1.1.utmcsr=google|utmccn=(organic)|utmcmd=organic|utmctr=(not%20provided)
8. Campaign Terms
209459845.1365484756.1.1.utmcsr=google|utmccn=(organic)|utmcmd=organic|utmctr=(not%20provided)

32. Customisation
• _setDomainName – Sets the domain to which all
cookies will be set.
• _setVisitorCookieTimeout – Sets the Google
Analytics visitor cookie expiration in milliseconds.
• _setSessionCookieTimeout – Sets the new session
cookie timeout in milliseconds.
• _setCampaignCookieTimeout – Sets the campaign
tracking cookie expiration time in milliseconds.

33. First Party Cookies
• Can only be used by the website that sets the
Cookies
• Can be overridden for sub domain and cross
domain tracking

34. Cross Domain Tracking
• www.toystore.com sets the GA Cookies
• They want to be used by blog.toystore.com
• They want to be used by www.bookstore.com
www.toystore.com
blog.toystore.com www.bookstore.com

35. Cross Domain Tracking
• Force GA into seeing blog.toystore.com and
www.bookstore.com as the same site as
www.toystore.com to share cookies
www.toystore.com
blog.toystore.com www.bookstore.com

36. Sub Domain Tracking
• Out of the box, GA sees the below as two separate
domains
• Use _gaq.push(['_setDomainName', 'toystore.com']);
www.toystore.com blog.toystore.com

37. Cross Domain Tracking
• Use _gaq.push(['_setDomainName', ‘toystore.com']);
_gaq.push(['_setAllowLinker', true]);
linker
www.toystore.com www.bookstore.com
• Use Linker Method e.g. <a href="http://www.bookstore.com"
onclick="_gaq.push(['_link',
'http://www.bookstore.com']); return false;">Book Store</a>

38. Hostname Filter
• Filter Type: Custom filter > Advanced
• Field A: Hostname Extract A : (.*)
• Field B: Request URI
• Extract: (.*)
• Output To: Request URI
• Constructor: $A1$B1

39. Goal Reports etc.
• Be Careful!
– Goals will also need hostname in as well as
pagename e.g. www.bookstore.com/index.php
rather than just index.php

40. Summary
• Cookies help to
– Differentiate one user from another
– Determine a relationship between sequential
pages
– Can only be used by the website that sets them
unless you configure your tracking code
– Do not collect any personal information
– Can misrepresent real life (unique
visitors, deletion, unacceptance)

41. The End

42. References
• http://devblog.springest.com/anatomy-of-
google-analytics-cookies
• http://andrescholten.net/
• https://developers.google.com/analytics/devg
uides/collection/analyticsjs/cookie-usage
• https://developers.google.com/analytics/devg
uides/collection/gajs/gaTrackingSite
• http://bit.ly/GATrouble

43. Visits/Sessions Ending?
More than 30 minutes have elapsed between pageviews for a
single visitor.
At the end of a day.
When any traffic source value for the user changes. Traffic
source information
includes:utm_source, utm_medium, utm_term, utm_content,
utm_id, utm_campaign, and gclid.
As before, if any of these events occur, then the next
pageview from the user will be the start of a new session.