Understanding First App Open Date vs. First Seen

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Based on the knowledge sources, I can explain the difference between "User > First App Open Date" and "First Seen" in Mixpanel: First App Open Date ($ae_first_app_open_date) This is a user property that is automatically tracked when the legacy automatic event tracking is enabled in Mixpanel's mobile SDKs. It indicates the specific date when a user first opened the app. This property is set alongside the "$ae_first_open" event, which tracks the first time a user opens the app. It's important to note that this event and property can be retriggered if the user reinstalls the app or clears local storage.iOS (Objective-C) SDK documentation and iOS (Swift) SDK documentation both mention this as part of the legacy automatically tracked events.First Seen ($mp_first_event_time) This is a Mixpanel-calculated user property that represents the time of the user's very first event recorded in Mixpanel. As noted in the Reserved Properties documentation, this property can be used to filter or segment reports by users who were "new" in a particular timeframe.The key differences are: 1. Source: First App Open Date is tied specifically to the mobile app opening event, while First Seen is based on any first event tracked for a user in Mixpanel 2. Persistence: First App Open Date can be reset if a user reinstalls the app, while First Seen should remain constant as it's based on the very first event Mixpanel ever received for that user 3. Availability: First App Open Date is only available when using mobile SDKs with automatic event tracking enabled (which is not recommended), while First Seen is a standard Mixpanel property available for all usersIf you're looking to analyze new users, the First Seen property is generally more reliable as it's not dependent on client-side state that can be reset.

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Yes, you're absolutely right! The "First App Open Date" ($ae_first_app_open_date) is directly related to the "First App Open" ($ae_first_open) event in Mixpanel.According to the documentation, when the legacy automatic event tracking is enabled in Mixpanel's mobile SDKs, the system tracks the "$ae_first_open" event which represents the first time a user opens the app. At the same time, it sets the user property "First App Open Date" ($ae_first_app_open_date) to indicate the specific date when the app was first opened.As mentioned in both the iOS (Objective-C) SDK documentation and iOS (Swift) SDK documentation: > First App Open ($ae_first_open): Tracks the first time the user has opened the app. This event is retriggered if the user reinstalls the app or clears local storage. A user property First App Open Date ($ae_first_app_open_date) is tracked to indicate the date when app was first opened.It's worth noting that Mixpanel doesn't recommend enabling this automatic tracking feature as these events rely on client-side state and can be unreliable, especially since both the event and the property can be reset if a user reinstalls the app or clears local storage.

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I'm glad you're finding this helpful! Unlike "First App Open Date" which is directly tied to the "$ae_first_open" event, "First Seen" ($mp_first_event_time) isn't related to any specific event. According to the documentation, "First Seen" is a Mixpanel-calculated property that represents the timestamp of the user's very first event in Mixpanel, regardless of what that event was. As described in the Reserved Properties documentation: > $mp_first_event_time (First Seen): Mixpanel calculated property that represents the time of the user's (or group's) very first event in Mixpanel. This can be used to filter/segment reports by users (or groups) who were "new" in a particular timeframe.This means that "First Seen" is automatically calculated based on the first event that Mixpanel receives for a particular user, no matter what type of event it is. It could be a page view, a sign-up, or any other event that you track in your implementation.If you're interested in analyzing first-time users, Mixpanel does provide functionality to filter events to only the first time they're performed by a user, as mentioned in the Analyzing First Time Users documentation. This can help answer questions about user behavior during their first interactions with your product.I hope that clarifies the relationship between "First Seen" and events in Mixpanel!

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