Understanding Initial Referrer: User vs. Event Level Differences

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The difference between "Initial Referrer" at the user level and at the event level in Mixpanel lies in how and when the property is set and updated: - Event-level Initial Referrer ($initial_referrer as an event property): - This property is attached to each event and represents the referring URL when the user first arrived on your site for that session or event. - It is collected and sent with every event tracked by the JavaScript SDK, as long as the Mixpanel cookie is present and not cleared. - The value remains the same for all subsequent events from the same user, unless the user clears their cookies or uses a different device/browser. - If the user lands directly (no referrer), the value is set to "$direct" see details here.- User-level Initial Referrer ($initial_referrer as a user property): - This property is stored on the user profile and represents the referring URL from the user's very first visit to your site. - It is only set the first time a user is identified and does not change on future visits, even if the user comes from a different referrer later. - This allows you to analyze the original acquisition source for each user, regardless of their subsequent sessions or events see details here.Summary: - The event-level property is attached to each event and can reflect the referrer for that event/session. - The user-level property is attached to the user profile and reflects the original referrer for the user's first visit, remaining constant for that user.This distinction is important for attribution analysis, as user-level properties help you understand original acquisition sources, while event-level properties provide context for individual actions or sessions Web Attribution.

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At the event level in Mixpanel, the difference between Referrer ($referrer) and Initial Referrer ($initial_referrer) is as follows: - Referrer ($referrer): This property represents the referring URL for the specific event—i.e., the URL of the page that led the user to the current page where the event was tracked. It is populated from the browser’s document.referrer property. If the user lands directly on the page (e.g., by typing the URL or using a bookmark), or if the referring website uses rel="noreferrer", this property may be omitted for that event.- Initial Referrer ($initial_referrer): This property captures the referring URL when the user first arrived on your site (i.e., their very first visit). It is stored in the Mixpanel cookie and sent with all future events from that user, as long as the cookie is not cleared. If the user was not referred (e.g., direct visit), the value is set to $direct. This value does not change for subsequent events or sessions unless the cookie is cleared Default Event Properties Web Attribution.In summary: - Referrer = Referring URL for the current event (may change per event). - Initial Referrer = Referring URL from the user's first-ever visit (remains constant for the user unless cookies are cleared).

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