"Work with a Facebook Marketing Partner to get deeper insights or measure across several ad networks" (Facebook - "Measuring for App Ads").
The acronym MMP is used to mean either the broad category of Facebook Mobile Marketing Partners, or more narrowly to mean Mobile Measurement Partners. The latter is a special subset of Facebook partners that have access to device-level attribution data. Branch has been vetted by Facebook and joined this group of partners in order to provide both granular analytics and true cross-channel reporting. We help you measure which installs, opens and conversion events should be attributed to Facebook ad campaigns versus other marketing efforts.
Updated almost 2 years ago