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Is GA source/medium defined at session level? Any post processing done after collection?

Visitor ✭ ✭ ✭
# 1
Visitor ✭ ✭ ✭

Hi everyone,


I have the following few questions which are inter-related, any information related to these will be highly appreciated:


(i) Does GA define source/medium for each session?

(ii) What all collected metrics are used to create the source/medium information available in GA reports?

(iii) GA also drops few cookies on pages -- utma, utmb, utmc, utmz etc. ( However, how does it use these cookies, are these used to calculate the source/medium?

  • Also technically, it feels like source/medium & utmz should give the same information or are these different?





1 Expert replyverified_user

Is GA source/medium defined at session level? Any post processing done after collection?

Rising Star
# 2
Rising Star

Hi Priyanka, 


Let me see if i can answer some of your questions: 

#1 Every new visitor has a source/medium . This is defined by incoming traffic and interpreted by Google. A new session doesn't mean a new session. A new session though if said user comes back via a new campaign. Remember: Google only will allow once set of source/medium/campaign per session. 


#2 Processing is simply the method of attaching the UTM data to the rest of the hits/data sent into Analytics. 


#3 Analytics uses cookies to remember what a user has done in the past as well as to distinguish between new and returning visitors. 


Let me know if this answers your questions! 

- Josh

Joshua, Rising Star
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Is GA source/medium defined at session level? Any post processing done after collection?

Explorer ✭ ✭ ✭
# 3
Explorer ✭ ✭ ✭

Hi Priyanka

in fact there are _umt* cookies that could cause some misunderstanding. These cookies are part of legacy 'standart analyitcs' and were used to store source\medium information.

With universal analyics there are only _ga and _gat coockies set by google analytics and they do not store any source information but unique user identifier clientId. Any data send to google analytics contains clientId. 

Later Google analytics aggregates data by clientIds and sets the source, medium and new session as described in the doc you've found (ii).

This means that visitor can access some site for the first time from google search page and so she'll be assigned some clientId within this site analytics tracking and serach engine referrer will be sent to analytics with the first pageview. And later her session (and all pageviews and events in this session) would get source\medium as google\organic in analytics. When getting back to the same site with paid search ads her clientId will be retrived for cookie and sent to analytics again with gclid or gclsrc parameter and then on server site this visit will be processed as 2nd session with google\cpc source\medium