Interview Questions › Root Cause Analysis

Sign-ups for your app are flat week-on-week

After 6 months of 8% week-on-week organic sign-up growth, total weekly sign-ups for your productivity app suddenly flattened (0% growth WoW). Diagnose the stall.

Context

Marketing ad spend is unchanged. Web traffic and app store impressions appear normal, but top-of-funnel account creation velocity plateaued.

Clarifying questions to ask first

• Did traffic volume flatten or did conversion rate drop?
• Is the plateau across all countries or specific geos?

How to approach it

1. Segment by acquisition channel (Organic Search, Paid Ads, Referrals, Direct)
2. Analyze the Sign-up Funnel: Landing Page -> CTA Click -> Auth Provider (Google/Apple/Email) -> Verification -> Workspace Creation
3. Check SEO traffic shifts, paid acquisition CAC saturation, and referral link degradation
4. Identify bottlenecks in auth third-party SSO or email delivery rates

Framework: Acquisition Channels -> Funnel Step-by-Step Dropoff -> Technical / Auth Integrations -> Market Saturation / Seasonality

Sample answer

• Google SSO rate limiting / consent screen error
• Email verification OTP deliverability degradation
• Paid marketing channel hitting audience saturation

1. Trace sign-up funnel by auth method
2. Isolate Email Sign-ups: OTP deliverability dropped from 98% to 74% due to spam filter blacklisting
3. Verify Google/Apple SSO remained steady at 85% conversion

Deliverability issue identified on transactional email IP domain; migrated to dedicated backup SES pool to restore 8% WoW growth trajectory.

What interviewers look for

• Organic Sign-up Velocity
• Landing Page Conversion Rate
• SSO Auth Success Rate
• Email Verification Rate