Attribution Channels

CQI Referrer Attribution classifies every session into one of nine channels. Classification happens server-side on first arrival using the HTTP referrer header and UTM parameters.

Channel priority

When more than one signal is present on a session, this priority order applies:

1. UTM parameters (utm_medium determines email, social, paid search, paid display, or campaign)
2. AI Referrer Taxonomy match
3. Known search engine referrer (organic search)
4. Known social platform referrer
5. Referral (any other external domain with a referrer)
6. Direct (no referrer, no UTM parameters)

Channel definitions

AI tools

Sessions where the HTTP referrer matches a domain in the AI Referrer Taxonomy. Includes traffic from ChatGPT, Gemini, Perplexity, Claude, Microsoft Copilot, Grok, Meta AI, and others. The full taxonomy is documented at AI Referrer Taxonomy.

Organic search

Sessions arriving from a search engine results page without paid click parameters. Detected by matching the referring domain against a list of known search engines (Google, Bing, DuckDuckGo, Yahoo, Baidu, Yandex, and others).

Social media

Sessions from social network domains: Facebook, Instagram, Twitter/X, LinkedIn, Pinterest, Reddit, TikTok, Snapchat, and others. Detection is by referrer domain.

Email

Sessions with utm_medium=email, or arriving from known webmail domains (Gmail, Outlook, Yahoo Mail, Apple Mail). The UTM parameter is the primary signal.

Paid search

Detected from the utm_medium URL parameter, not from the referrer header. utm_medium set to cpc or ppc is classified as Paid search.

Paid display

Also detected from utm_medium. utm_medium set to display is classified as Paid display. Any other utm_medium value not covered by the categories above is classified as Campaign.

Campaign (UTM)

Sessions carrying UTM parameters that do not map to a more specific channel.

Referral

Sessions from a referring domain that is not in any other taxonomy (not AI, not social, not search, not email). Any inbound link from an external site that is not otherwise classified.

Direct

Sessions with no HTTP referrer and no UTM parameters. Includes typed URLs, browser bookmarks, and some mobile app traffic where the referrer is stripped.

Common questions

What happens if a session matches more than one channel signal? +

The plugin applies the priority order listed above and assigns the first match. UTM parameters are checked first, so a session with both a social media referrer and a utm_source=newsletter parameter is classified as Campaign, not Social media.

Can a session change channel after it is first classified? +

No. Classification happens once, on first arrival, and is fixed for that session. Subsequent page views in the same session do not re-evaluate or overwrite the original channel, which is why self-referral exclusion matters: without it, internal navigation could otherwise look like a new referral.

Why might Referral traffic be higher than expected? +

Referral is the catch-all channel for any referring domain not matched by a more specific taxonomy. If a partner site, directory, or aggregator sends traffic and is not in the search, social, or AI taxonomy, it appears as Referral. Pro users can drill down into Referral to see the actual source domains.

Does a session ever get classified into more than one channel? +

No. Every session is assigned to exactly one of the nine channels. The priority order exists specifically to resolve cases where more than one signal is present, so the result is always a single, deterministic channel.

Are paid search and organic search ever confused with each other? +

Paid search and paid display are both detected from the utm_medium URL parameter, not from the referrer header, so accurate detection depends on your paid links carrying UTM tags. If a paid link has no UTM parameters, the session is classified by referrer instead, typically landing in Organic search, Referral, or Direct.

CQIP is a methodology standard, not a technology stack. Implementations exist for static PHP sites, WordPress, page generators, and other document management systems. The platform is the implementation detail - the standard and the eight canonical block types are consistent across all implementations.