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Fitness App MAU Drop Analysis
Complete RCA framework for a B2C mobile fitness app experiencing 10% monthly active user decline. Demonstrates fitness-specific hypotheses including wearable integrations, post-New Year's seasonality, and workout content quality.
Input
What you provide to the skill
Monthly active users dropped 10% this month. We’re a B2C mobile fitness app.
Output
What the skill generates for you
=== ROOT CAUSE ANALYSIS FRAMEWORK ===
STEP 1: CLARIFYING QUESTIONS (Ask These First)
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1. SCOPE: Is the 10% MAU drop uniform across all user segments, or concentrated in specific cohorts (new vs. returning users, free vs. paid, age groups, fitness goals)?
- Why ask: Helps narrow whether it's a broad product issue or specific to certain user types
2. TIMEFRAME: Did the drop happen suddenly (week 1 of the month) or gradually throughout the month?
- Why ask: Sudden = likely technical issue or external event; Gradual = product degradation or competitive shift
3. PLATFORMS: Is the drop affecting iOS and Android equally, or is it platform-specific?
- Why ask: Platform-specific drop suggests technical issue, app store change, or OS update conflict
4. GEOGRAPHY: Is this global or concentrated in specific regions/countries?
- Why ask: Region-specific suggests local competition, cultural events, or app store visibility changes
5. METRIC DEFINITION: Has the MAU definition changed? Any instrumentation or tracking updates?
- Why ask: Data quality issues are surprisingly common and easy to rule out
6. RECENT CHANGES: Were there any feature releases, experiments, redesigns, or subscription/pricing changes this month?
- Why ask: Temporal correlation with product changes is the most common root cause
7. RETENTION PATTERNS: Are users churning (not coming back) or just engaging less frequently (still active but below 30-day threshold)?
- Why ask: Churn vs. frequency issues have different root causes and solutions
STEP 2: MECE HYPOTHESIS FRAMEWORK
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CATEGORY A: INTERNAL - PRODUCT CHANGES (High Priority - Check First)
1. Recent feature release degraded core workout experience (broken tracking, UI bugs, missing functionality)
Impact: CRITICAL | Likelihood: High | Data: MAU by app version, crash/error rates by version, feature usage rates
2. Onboarding flow changes reduced new user activation
Impact: High | Likelihood: Medium | Data: New user MAU trend, onboarding completion rates, D1/D7 retention by cohort
3. Content quality declined (fewer new workouts, stale recommendations, repetitive plans)
Impact: High | Likelihood: Medium | Data: Workout completion rates, content consumption, user engagement per session
4. Notification changes (reduced frequency, relevance, or broken delivery)
Impact: High | Likelihood: Medium | Data: Push notification send rates, open rates, sessions started from push
5. Paywall or subscription changes drove away free users or failed conversions
Impact: High | Likelihood: Medium | Data: MAU by subscription tier, paywall impression rates, conversion rates
6. Social/community features removed or degraded (leaderboards, challenges, sharing)
Impact: Medium | Likelihood: Medium | Data: Social feature usage, users with social connections, session frequency
CATEGORY B: INTERNAL - TECHNICAL/INFRASTRUCTURE (High Priority)
7. App performance degradation (slow load times, laggy workout tracking, syncing issues)
Impact: High | Likelihood: High | Data: P95 load times, session abandonment, app performance metrics
8. Platform-specific crashes or bugs (especially after iOS/Android OS updates)
Impact: High | Likelihood: High | Data: Crash rates by platform/OS version, error logs, app store reviews
9. Wearable/device integration broken (Apple Watch, Fitbit, Garmin sync failures)
Impact: High | Likelihood: Medium | Data: Device sync success rates, error logs, MAU by integration type
10. Authentication or login issues preventing access
Impact: CRITICAL | Likelihood: Low | Data: Login success rates, auth error rates, session start rates
11. Background activity tracking broken (steps, GPS routes not recording)
Impact: High | Likelihood: Medium | Data: Background tracking events, GPS accuracy, user complaints
CATEGORY C: EXTERNAL - COMPETITION & MARKET (Medium Priority)
12. Major competitor launched viral feature or aggressive free tier
Impact: High | Likelihood: Medium | Data: App store rankings, competitive install rates, social media mentions
13. Competing fitness app running heavy user acquisition or retention campaign
Impact: Medium | Likelihood: Medium | Data: Category rankings, competitor ad spend (if available), market research
14. Industry-wide fitness app fatigue or trend shift (e.g., return to in-person gyms)
Impact: Medium | Likelihood: Low | Data: Benchmark against other fitness apps, industry reports
15. High-profile influencer or celebrity switched to competitor or stopped promoting fitness
Impact: Low | Likelihood: Low | Data: Social media trends, referral traffic changes
CATEGORY D: EXTERNAL - SEASONALITY & EVENTS (Medium Priority)
16. Post-New Year's resolution drop-off (if this is February/March)
Impact: High | Likelihood: High | Data: Historical year-over-year MAU patterns, seasonal trends
17. Weather/seasonal changes (summer vacation, outdoor exercise replacing app usage)
Impact: Medium | Likelihood: Medium | Data: Historical patterns, geography correlation
18. Return to work/school after break reduced workout time availability
Impact: Medium | Likelihood: Medium | Data: Session time trends, weekly usage patterns
CATEGORY E: EXTERNAL - REGULATORY & PLATFORM POLICY (Low-Medium Priority)
19. App store visibility changes (algorithm update, category changes, ranking drop)
Impact: High | Likelihood: Low | Data: App store rankings, organic install rates, search visibility
20. iOS/Android policy changes affecting tracking, permissions, or background activity
Impact: Medium | Likelihood: Low | Data: Permission grant rates, tracking authorization rates (iOS 14.5+)
21. Negative PR or privacy concerns affecting brand reputation
Impact: Medium | Likelihood: Low | Data: Social media sentiment, news mentions, brand search trends
CATEGORY F: DATA QUALITY & MEASUREMENT (Check Early!)
22. Instrumentation bug undercounting active users
Impact: CRITICAL | Likelihood: Medium | Data: Sanity checks (DAU/MAU ratio, revenue correlation, session counts)
23. Data pipeline failure or delay in processing events
Impact: CRITICAL | Likelihood: Low | Data: Data freshness, pipeline logs, metric anomaly detection
24. MAU definition changed (e.g., tighter definition of "active", bot filtering added)
Impact: High | Likelihood: Low | Data: Check with data/analytics team, definition documentation
STEP 3: PRIORITIZATION MATRIX
------------------------------
CHECK FIRST (High Impact × High Likelihood):
→ App performance degradation (#7) - Most common user churn driver in mobile apps
→ Platform crashes/bugs (#8) - Can immediately drive users away
→ Recent feature release issues (#1) - High correlation with sudden drops
→ Onboarding changes (#2) - Affects new user activation directly
→ Post-New Year's drop-off (#16) - If timing aligns (Feb/March), this is near-certain
→ Instrumentation bug (#22) - ALWAYS check data quality early to avoid false alarms
CHECK SECOND (High Impact × Medium Likelihood OR Quick to Verify):
→ Notification changes (#4) - Easy to verify, high impact on re-engagement
→ Content quality decline (#3) - Gradual effect but verifiable
→ Wearable integration issues (#9) - Fitness apps heavily rely on this
→ Paywall changes (#5) - Can check conversion/tier data quickly
→ Major competitor launch (#12) - External validation available
CHECK THIRD (Lower Impact or Lower Likelihood):
→ App store visibility (#19)
→ Social features degradation (#6)
→ Authentication issues (#10) - Would see more dramatic drop if widespread
→ All remaining hypotheses based on context clues
STEP 4: STRATEGIC DATA REQUESTS
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1. SEGMENTATION (narrows scope fast):
"Can you show me MAU trend over the past 3 months segmented by:
- Platform (iOS vs. Android)
- User type (new users acquired this month vs. returning users from prior months)
- Subscription tier (free vs. paid)
- Geography (top 5 countries)
- User engagement level (power users with 10+ sessions/month vs. casual users)"
2. TECHNICAL HEALTH (rules out infrastructure):
"Can you provide for the past 2 months:
- App crash rates and error rates by day (segmented by platform/OS version)
- App performance metrics (P95 load times, session abandonment rates)
- Wearable sync success rates (Apple Health, Google Fit, device integrations)
- Background tracking event volume"
3. TEMPORAL CORRELATION (what changed when):
"What changed in the past 2 months:
- Any feature releases, redesigns, or experiments started/ended?
- Any changes to onboarding, notifications, paywalls, or content?
- App store updates or submission timing?
- Any app version rollout schedules or forced update requirements?"
4. RETENTION & BEHAVIORAL PATTERNS (understand symptoms):
"Can you show me for the past 3 months:
- D1, D7, D30 retention rates by cohort (month of acquisition)
- Average sessions per MAU
- Average workout completion rate
- Session length and workout minutes per user
- Push notification engagement (sends, opens, sessions from push)
- Feature adoption rates (social features, premium content, challenges)"
5. DATA QUALITY CHECKS (rule out measurement issues):
"Sanity checks:
- DAU/MAU ratio trend (should be relatively stable)
- Revenue trend (should correlate with MAU if real drop)
- Total session count trend
- Any recent analytics instrumentation changes or data pipeline updates?"
6. EXTERNAL CONTEXT (if relevant based on above):
"External factors:
- App store ranking trends (category rank, keyword rankings)
- Competitor app download/ranking trends
- Historical seasonality (YoY comparison for same month)"
STEP 5: INTERVIEW ANSWER STRUCTURE (Use This Flow)
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1. CLARIFY (2-3 minutes):
"Before diving into hypotheses, let me clarify the situation to narrow my focus. First, I'd like to understand if this 10% MAU drop is uniform across all user segments or if certain cohorts are driving it—specifically new vs. returning users, iOS vs. Android, or geographic regions. Second, did this happen suddenly in the first week or gradually throughout the month? Third, has anything changed in how we measure MAU? And finally, were there any product releases, experiments, or marketing changes this month?"
2. FRAMEWORK (1 minute):
"I'll use a MECE framework to organize potential root causes into Internal Product Changes, Internal Technical Issues, External Competition & Market, Seasonality, Platform Policy, and Data Quality categories. This ensures we systematically cover all possibilities without overlap."
3. HYPOTHESES (5-7 minutes):
"Let me walk through the most likely causes in each category:
Starting with Internal Product Changes—the most common culprit. A recent feature release could have degraded the core workout experience through bugs, broken tracking, or UI issues. I'd check MAU by app version and crash/error rates. Second, onboarding flow changes might have reduced new user activation, which I'd verify by looking at new user MAU trends and D1/D7 retention. Third, content quality may have declined—fewer new workouts or stale recommendations—which would show up in workout completion rates and engagement per session. Fourth, notification changes could be reducing re-engagement; I'd check push send rates and open rates.
Moving to Internal Technical Issues—app performance degradation is a major driver of churn in mobile fitness apps. Slow load times or laggy tracking would show up in session abandonment metrics. Platform-specific crashes, especially after iOS or Android OS updates, could be affecting one platform disproportionately. Wearable integration issues—like broken Apple Watch or Fitbit syncing—are critical for fitness apps and would appear in sync success rates.
For External factors—if this is February or March, post-New Year's resolution drop-off is highly likely and would show up in year-over-year seasonal patterns. A major competitor launching a viral feature or aggressive free tier could pull users away, which I'd verify through app store rankings. Seasonal changes like summer weather could shift users to outdoor activities.
Finally, Data Quality—I'd check for instrumentation bugs that might be undercounting MAU. Sanity checks include verifying DAU/MAU ratio trends and ensuring revenue correlates with the drop."
4. PRIORITIZATION (2-3 minutes):
"Given what we know, I'd prioritize investigating in this order: First, check if this is a data quality issue—quick sanity checks on DAU/MAU ratio and revenue trends. Second, if timing aligns, verify post-New Year's seasonality against historical patterns. Third, investigate app performance and crashes, as these are the most common drivers of sudden engagement drops in mobile apps. Fourth, analyze MAU by app version to correlate with any recent releases. Fifth, segment by platform and user type to narrow the scope. This prioritization balances impact, likelihood, and ease of verification."
5. DATA REQUESTS (2-3 minutes):
"To test these hypotheses, I'd request the following data in this order: First, MAU segmented by platform, user cohort, subscription tier, and geography over the past 3 months—this narrows scope fastest. Second, technical health metrics including crash rates, performance metrics, and wearable sync success rates. Third, a timeline of all product changes in the past 2 months to identify temporal correlations. Fourth, retention and behavioral patterns including D7/D30 retention by cohort, sessions per MAU, and workout completion rates. Finally, data quality sanity checks including DAU/MAU ratio and revenue correlation."
6. NEXT STEPS (1-2 minutes):
"Once we have this data, I'd drill into the top hypotheses based on what the segmentation reveals. If it's platform-specific, I'd investigate technical issues on that platform. If it's cohort-specific, I'd look at onboarding or acquisition quality changes. If it's uniform and gradual, I'd investigate product experience degradation or competitive factors. After isolating the root cause, I'd recommend specific fixes—whether technical, product, or content—and validate the fix through an A/B test before full rollout, measuring impact on D7 retention and re-engagement."
COMMON MISTAKES TO AVOID:
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❌ Jumping to "it's seasonal" without checking year-over-year data
❌ Not segmenting by new vs. returning users (very different root causes)
❌ Missing post-New Year's resolution timing if it's Feb/March (extremely common in fitness)
❌ Forgetting wearable integrations (critical for fitness apps)
❌ Only considering product changes without checking technical health
❌ Not asking about retention vs. frequency (churn vs. engagement issues)
❌ Missing app store ranking/visibility changes
❌ Not checking data quality early (instrumentation bugs are common)
❌ Assuming it's competition without verifying app store trends
❌ Not requesting specific breakdowns in data (vague "show me more data" requests)
❌ Forgetting to correlate with revenue (sanity check for real vs. measurement drop)
❌ Missing notification engagement as a key re-engagement driver
About This Skill
Generate comprehensive MECE-based RCA frameworks for PM interview metric investigation questions with prioritized hypotheses and answer structures.
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