Your campaign should be tracked on into your s.campaign (which has a 1 week attribution by default) and you can set up custom eVars (with Visit or Week, etc) to do additional tracking..,
When a user arrives on your site (https://www.domain.com/?cid=paid_google_12345 or https://www.domain.com/?utm_source=google&utm_medium=paid&utm_campaign=12345)
You should track your campaign on the page view:
s.campaign = paid_google_12345
or
s.campaign = medium:paid|source:google|campaign:12345
and maybe you also want:
s.eVar1 = paid
s.eVar2 = google
s.eVar3 = 12345
You do not, and should not resend this value on any clicks on that same page, or on any additional pages on the site.. the attribution will carry this through until the expiry, or until a new campaign is passed.
Visit 1 (campaign "paid_google_12345")
- Page A
- Page View metric triggered
- Campaign set to "paid_google_12345"
- Campaign Instance metric triggered (this metric is when the value is actually set)
- eVar1 set to "paid"
- eVar1 Instance metric triggered
- eVar2 set to "google"
- eVar2 Instance metric triggered
- eVar3 set to "12345"
- eVar3 Instance metric triggered
- Action 1 (on Page A)
- Custom Link equals "some link"
- Custom Link Instance triggered
- Campaign not set, but will retain value "paid_google_12345" due to 1 Week attribution
- Campaign Instance metric not triggered
- eVar1 not set, but will retain value "paid" due to Visit attribution
- eVar1 Instance metric not triggered
- eVar2 not set, but will retain value "google" due to Visit attribution
- eVar2 Instance metric not triggered
- eVar3 not set, but will retain value "12345" due to Visit attribution
- eVar3 Instance metric not triggered
- Page B
- Page View metric triggered
- Campaign not set, but will retain value "paid_google_12345" due to 1 Week attribution
- Campaign Instance metric not triggered
- eVar1 not set, but will retain value "paid" due to Visit attribution
- eVar1 Instance metric not triggered
- eVar2 not set, but will retain value "google" due to Visit attribution
- eVar2 Instance metric not triggered
- eVar3 not set, but will retain value "12345" due to Visit attribution
- eVar3 Instance metric not triggered
Visit 2 (no campaign) - within a week of Visit 1
- Page A
- Page View metric triggered
- Campaign not set, but will retain value "paid_google_12345" due to 1 Week attribution
- Campaign Instance metric not triggered
- eVar1 not set, Visit has expired
- eVar1 Instance metric not triggered
- eVar2 not set, Visit has expired
- eVar2 Instance metric not triggered
- eVar3 not set, Visit has expired
- eVar3 Instance metric not triggered
- Action 1 (on Page A)
- Custom Link equals "some link"
- Custom Link Instance triggered
- Campaign not set, but will retain value "paid_google_12345" due to 1 Week attribution
- Campaign Instance metric not triggered
- eVar1 not set, Visit has expired
- eVar1 Instance metric not triggered
- eVar2 not set, Visit has expired
- eVar2 Instance metric not triggered
- eVar3 not set, Visit has expired
- eVar3 Instance metric not triggered
- Page B
- Page View metric triggered
- Campaign not set, but will retain value "paid_google_12345" due to 1 Week attribution
- Campaign Instance metric not triggered
- eVar1 not set, Visit has expired
- eVar1 Instance metric not triggered
- eVar2 not set, Visit has expired
- eVar2 Instance metric not triggered
- eVar3 not set, Visit has expired
- eVar3 Instance metric not triggered
Visit 3 (campaign "paid_social_5555") within a week of Visit 1
- Page A
- Page View metric triggered
- Campaign set to "paid_social_5555" (overwriting the previous value)
- Campaign Instance metric triggered (this metric is when the value is actually set)
- eVar1 set to "paid"
- eVar1 Instance metric triggered
- eVar2 set to "social"
- eVar2 Instance metric triggered
- eVar3 set to "5555"
- eVar3 Instance metric triggered
- Action 1 (on Page A)
- Custom Link equals "some link"
- Custom Link Instance triggered
- Campaign not set, but will retain value "paid_social_5555" due to 1 Week attribution
- Campaign Instance metric not triggered
- eVar1 not set, but will retain value "paid" due to Visit attribution
- eVar1 Instance metric not triggered
- eVar2 not set, but will retain value "social" due to Visit attribution
- eVar2 Instance metric not triggered
- eVar3 not set, but will retain value "5555" due to Visit attribution
- eVar3 Instance metric not triggered
- Page B
- Page View metric triggered
- Campaign not set, but will retain value "paid_social_5555" due to 1 Week attribution
- Campaign Instance metric not triggered
- eVar1 not set, but will retain value "paid" due to Visit attribution
- eVar1 Instance metric not triggered
- eVar2 not set, but will retain value "social" due to Visit attribution
- eVar2 Instance metric not triggered
- eVar3 not set, but will retain value "5555" due to Visit attribution
- eVar3 Instance metric not triggered
When you look at your report, you can use the "Campaign Instance" or "eVarX Instances" to get the "entries" for your campaigns, you can use "Page Views" to get all page views attributed to those campaigns. You can also correlate your Custom Link Instances, any Conversion Events (like Orders) against your Campaign or eVars to see what the last touch (within the scope of the dimension - ie. week or visit) to see what conversions came from your campaigns... You can also use custom attribution modelling to look at Participation or another model, or look at a longer attribution (i.e. 1 Month, 6 Months, etc)