How do I approach Analytics & Experimentation interview questions?

Analytics & Experimentation questions require understanding of core concepts and practice. PracHub provides solutions with explanations to help you master analytics & experimentation interviews.

What difficulty level is this interview question?

This is a medium difficulty Analytics & Experimentation question, commonly asked during HR Screen rounds at Instacart.

What role is this question designed for?

This question is commonly asked for Data Scientist candidates at Instacart during technical interviews.

Diagnose and fix low conversion rigorously | Instacart Interview Question

Quick Overview

This question evaluates a Data Scientist's competency in analytics and experimentation, covering instrumentation validation, funnel and segmentation analysis, causal inference methods (holdouts/DiD), system reliability diagnostics, statistical power and sample-size estimation, and the ability to synthesize findings into executive-level impact statements. It is commonly asked to determine whether a candidate can distinguish measurement or product regressions from marketing-mix shifts and to demonstrate both conceptual understanding of causal inference and practical application of data querying, metric definition, and experiment design in the Analytics & Experimentation domain.

Scenario

Week-over-week, checkout conversion fell from 42% to 35% after a new promo banner shipped. Traffic volume is flat, the marketing mix shifted 10% toward paid social, and payment failures rose slightly. You need to isolate the root cause and recommend next steps.

Task

Outline a concise, step-by-step investigation and testing plan that:

Validates instrumentation and precisely defines the conversion metric.
Builds a funnel and segments results by device, geo, and new vs. returning users.
Inspects latency and error/timeout rates across the checkout stack.
Uses holdouts or a difference-in-differences (DiD) approach to separate promo impact from channel-mix shifts.
Specifies the minimal queries/metrics to pull to execute the plan.
Estimates the statistical power and sample size for a rollback or fix-forward A/B test.
Summarizes the executive-level insight you would present, including expected revenue impact and recommended next actions.

Diagnose and fix low conversion rigorously

Quick Overview