Wikimedia Apps/Team/iOS/Analysis

This is a WIP.

Webreqeust
The webrequest datasets contain logs of all the hits to the WMF's servers (specifically, the Varnish servers). This includes requests for page HTML, images, CSS, and Javascript, as well as requests to the API. For privacy reasons, this data is purged after 90 days. We use the webrequest table and its aggregated tables for app analysis. Specifically: Please note that webrequest data doesn't contain users' appInstallID if they choose not to send usage reports to the Wikipedia iOS app, regardless of whether they agree to send analytics data to Apple at the system level or not.
 * mobile apps uniques: Count how many different Android and iOS Wikipedia mobile apps installs accessed Wikimedia sites during the given day or month, determined as the number of app uuids appearing in the webrequest table (via the X-Analytics header or formerly the query part of the URL).
 * mobile apps session metrics: Contain aggregate stats about pageview sessions on the Android and iOS Wikipedia mobile apps, updated weekly. Please note the caveats of this dataset as the metrics may not be what you expected.
 * Pageview_hourly

Event logging schema
The EventLogging data collects metrics on how users interact with the app. Currently, the Wikipedia iOS app is sending data to the following eventlogging schemas: MobileWikiAppDailyStats, MobileWikiAppCreateAccount, MobileWikiAppEdit, MobileWikiAppLogin, MobileWikiAppProtectedEditAttempt, MobileWikiAppToCInteraction, MobileWikiAppNavMenu, MobileWikiAppSearch, MobileWikiAppShareAFact, MobileWikiAppSavedPages.

Please note that for some schemas, iOS is using a different revision from Android. Check the schema pages and their discussion pages for more details.

iTunes Connect and App Annie
iTunes Connect provides various metrics to measure the app's performance in App Store such as impression, product page views and app units. It also provides some usage metric from users who agree to share their diagnostics and usage information with Apple, such as sessions, active devices and retention. Within iTunes Connect, App Analytics displays data from devices running iOS 8 or tvOS 9, or later, and that data is displayed only when a certain number of data points are available; Sales and Trends is recorded when a customer initiates a transaction on the App Store. There are some differences in the units reporting between App Analytics and Sales and Trends for the following reasons : Links to documentation of iTunes Connect: App Annie is a third party app market data provider. It is integrated with iTunes Connect and basically provides the same metrics as iTunes Connect and App Store, but with some estimation and better visualization. We've seen some discrepancies between the numbers provided by iTunes Connect and App Annie. Some can be explained by that App Annie's data is based on Pacific Time. We are contacting App Annie for the reason why the Downloads number under "Store Views" tab and the Downloads number under "Downloads" tab are different.
 * 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).
 * iTunes Connect - Measure App Performance
 * iTunes Connect - Sales and Trends Guide
 * iTunes Connect - App Analytics Guide

Metrics
Among all the metrics listed below, the following are the core metrics for the iOS Wikipedia app that WMF has been tracking on a regular basis since around 2015, reported in the Readers team's quarterly metrics meetings and (partially) in the Audiences department's monthly readers metrics update: daily pageviews, daily installs (aka. app units), 7-day retention, ratings, pageviews per session, session length and sessions per user.

Browse and Install
Useful ratio:
 * 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.

Usage
Useful ratio:
 * Daily Active Devices / 30 Day Active Devices: The ratio of Daily Active Devices to 30 Day (roughly monthly) Active Devices displays an engagement level of the active user base . This ratio reveals how much of our monthly active user base checks in on a daily basis.
 * Sessions per Active Device: The ratio of Daily Sessions to Daily Active Devices is used to understand the number of sessions an average active device launches each day. We also reported sessions per user in mobile apps session metrics. However, it is based on users who have at least one pageviews (thus the  -- the number of users -- is less than the number reported by mobile_apps_uniques), and a session is defined as a sequence of pageviews from the same app ID that does not exceed 30 minutes of inactivity.
 * Pageviews per session: Reported in mobile apps session metrics. This is based on users who have at least one pageviews and a session is defined as a sequence of pageviews from the same app ID that does not exceed 30 minutes of inactivity.