Fabric data is different from iTunes Connect data
Our daily new user count from Fabric is consistently larger than the app units per day we get from iTunes Connect.
Fabric defines daily new users as
The number of new apps for all devices visible on the given day.
And iTunes connect defines app units as
The number of app downloads that are first downloaded in the App Store using iOS 8 or tvOS 9 or later. App updates, downloads from the same Apple ID to other devices, and repeated downloads to the same device are not counted. Family Sharing downloads are included with free apps, but not paid apps.
What can cause this discrepancy? I see many reasons why Fabric might report fewer numbers (like users downloading an app but never opening it, or waiting too long to open it ), but not the other way around. Our average developer opt-out rate is 23%, but this does not affect the App Units number if I'm not mistaken.
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Is your app available on iPhone and iPad? If so, the fact that, as you noted, Apple does not believe that downloading from the same Apple ID to other devices can cause this inconsistency? You can install iPhone apps on your iPad even if it's not officially supported, so this rule may still affect your app. Also, if your app is a paid app, Family sharing rules will also affect the numbers. I really wondered how iTunes calculates new users, so thanks for this information!
I'm not sure why the numbers on your Fabric are significantly higher, because for my application they alternate a little.
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Hope you could get an answer. If not follow the link below http://help.apple.com/itc/appanalytics/#/itc7bea1545f
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