Why Firebase and Google Analytics metrics doesn't match?

Question

I integrated both GA and Firebase to my app and I'm having confusing analytics metrics specifically Active user and total session.

Firebase: GA: As you can see the count doubled on GA.

Firebase: Session 19K, Active user: 9.7K

GA: Active user: 13K (3.3K off), Session: 53K (34K off)

As you can see Total session and Active user do not match at all on the same period of time. This is so confusing as these metrics are extremely important for marketing.

I'm wondering if anyone had a similar issue? Could I be doing anything wrong ?

SDKs versions used: FirebaseAnalytics (= 4.2.0), FirebaseCore (= 4.0.20) and GoogleAnalytics (3.17.0)

Answer 1

Definition of a session is different between Firebase and Google Analytics.

• Google Analytics: a single hit will initiate a session. More info
• Firebase: Firebase records the first hit but don't start a session until the user has interacted with the page for 10s (by default). More info