Faysal Ahmed
Chapter 9

Mobile Analytics & Experimentation

Instrumenting Mobile Events

Every screen view, tap, swipe, and transaction should be logged. Define a tracking plan before writing code:

{
  "event": "purchase_completed",
  "properties": {
    "product_id": "premium_monthly",
    "price": 9.99,
    "currency": "USD",
    "payment_method": "apple_pay"
  }
}

Use a schema registry so iOS, Android, and backend teams log the same event with consistent property names and types.

Analytics SDKs

ToolStrengths
Firebase AnalyticsFree, integrates with Crashlytics and Google Ads
MixpanelPowerful cohorts, retention analysis, and user profiles
AmplitudeBehavioural analytics, funnel analysis, and predictive models
SegmentMiddleware — pipe events to multiple destinations without SDK changes

Choose one primary tool and avoid logging the same event into five SDKs (performance cost).

A/B Testing on Mobile

Mobile A/B testing is harder than web because:

  • App store review delays experiment deployment.
  • Client-side experiments require feature flags and kill switches.
  • Statistical significance takes longer with smaller mobile conversion rates.

Platforms: Firebase Remote Config, LaunchDarkly, Optimizely.

Feature Flags

Feature flags decouple deploy from release. On mobile, this is critical for:

  • Canary launching new features
  • Turning off broken features without a hotfix
  • Running A/B experiments
  • Gradually rolling out to user segments

Metrics to Watch During Experiments

  • Primary: The metric the experiment targets (conversion, retention, revenue)
  • Guardrail: Crash rate, ANR rate, session length (must not degrade)
  • Secondary: Downstream effects on other parts of the product

Next: Chapter 10 — Mobile Product Launch & Operations