Wikimedia Apps/Team/iOS/Analysis

Data Sources
Measure App Performance: https://help.apple.com/itunes-connect/developer/#/dev5340bf481

iTunes Connect Sales and Trends Guide: https://help.apple.com/itc/appssalesandtrends/

App Analytics Guide: https://help.apple.com/itc/appanalytics/

Discrepancy between iTunes and App Annie: People seem to think App Annie’s estimate is more reliable than iTunes Connect, but there is no solid proof.
 * App Analytics only displays data from devices running iOS 8 or tvOS 9, or later. Sales and Trends displays all sales data from devices running iOS, tvOS, and macOS.
 * App Analytics data is based on Coordinated Universal Time (UTC). By default, Sales and Trends data is shown in Coordinated Universal Time (UTC), but users can change the time zone to Pacific Standard Time (PST).
 * App Annie data is based on Pacific Time.

Metrics
Useful ratio: Useful ratio:
 * Dimensions are the variables by which this metric can be broken down or filtered. See more details: https://help.apple.com/itunes-connect/developer/#/itc21781223f
 * Conversion Rate: The ratio of app units to impression or product page views. Depending on your purpose, either the count of views or unique devices can be the denominator.
 * Daily Active Devices / 30 Day Active Devices: The ratio of Daily Active Devices to 30 Day (roughly monthly) Active Devices to display an engagement level of your active user base . This ratio reveals how much of your monthly active user base checks in on a daily basis.
 * Sessions per Active Device: The ratio of daily average Sessions to Daily Active Devices to understand the number of sessions an average active device plays each day.