Interview Questions › Root Cause Analysis

Add to Cart -> Purchase drop-off increased at payment step

Drop-off between the final payment selection screen and order confirmation increased from 14% to 26% following a multi-currency checkout redesign.

Context

Users are successfully adding items and entering delivery addresses, but abandoning on the final review & pay modal.

Clarifying questions to ask first

• Is the drop isolated to international cross-border shoppers or domestic?
• Which specific payment methods have the highest abandonment?

How to approach it

1. Segment checkout funnel by Payment Method (Apple Pay, Klarna/BNPL, Credit Cards, PayPal)
2. Analyze foreign exchange fee disclosures and dynamic currency conversion warnings
3. Investigate technical SDK timeouts and 3D-Secure modal iframe rendering bugs on mobile Safari
4. Check unexpected taxes, duties, or shipping recalculations revealed on the final screen

Framework: Checkout Step Isolation -> Payment Method Breakdown -> Pricing / FX Fee Transparency -> Browser & Technical JS Errors

Sample answer

• Unclear FX conversion fees added at the final step surprising shoppers
• Klarna BNPL widget failing to render on iOS Safari webviews
• Mandatory 3DS biometric authentication failing due to third-party bank pop-up blocker

1. Browser segmentation: Mobile Safari checkout conversion collapsed by 40%
2. Investigation: Safari 17 pop-up blocking prevented 3DS bank authorization window from opening

Safari 17 pop-up blocker broke 3DS iframe authorization; implemented inline 3DS redirect flow to recover $3.4M in weekly abandoned checkouts.

What interviewers look for

• Payment Screen Conversion %
• BNPL vs Card Abandonment
• 3DS Authentication Success Rate
• Safari vs Chrome Conversion