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Design an email flu-shot experiment

Last updated: Mar 29, 2026

Quick Overview

This question evaluates end-to-end experiment design and causal inference skills for a Data Scientist, including A/B testing and randomization choices, interference control, metric definition and power/sample-size calculation, outcome sourcing from claims/EHR/pharmacy feeds, cadence/MVT design, seasonality controls, and compliance/privacy considerations. It is commonly asked in analytics and experimentation interviews because it tests both practical application and conceptual understanding of field experiment planning, real-world data challenges (missing outcomes, claim lag), and analysis decisions (ITT vs per-protocol, multiple testing) within the Analytics & Experimentation domain.

  • hard
  • CVS Health
  • Analytics & Experimentation
  • Data Scientist

Design an email flu-shot experiment

Company: CVS Health

Role: Data Scientist

Category: Analytics & Experimentation

Difficulty: hard

Interview Round: Technical Screen

Design an end-to-end email campaign to increase verified flu vaccinations within 30 days among eligible members. Specify (a) targeting and exclusion rules, (b) the randomization unit (individual vs household vs clinic) and how you will limit spillover/interference, (c) holdout structure (A/A, A/B, multi-arm) and seeding, (d) primary and guardrail metrics and how you will obtain ground-truth outcomes (e.g., claims/EHR, pharmacy feeds) and handle missing outcomes when shots occur outside our network, (e) power analysis: estimate required sample size if baseline vaccination is 2.0% over the window and you expect a 20% relative uplift; use alpha=0.05 and power=0.8 with option for unequal allocation, (f) cadence/frequency capping and multivariate subject-line/creative testing without contaminating the main test, (g) seasonality/holiday controls and overlapping campaigns, (h) compliance/privacy constraints (opt-outs, HIPAA) and their analytical implications, and (i) the analysis plan (intention-to-treat vs per-protocol), heterogeneity reads, and a backstop causal method if randomization is partially broken.

Quick Answer: This question evaluates end-to-end experiment design and causal inference skills for a Data Scientist, including A/B testing and randomization choices, interference control, metric definition and power/sample-size calculation, outcome sourcing from claims/EHR/pharmacy feeds, cadence/MVT design, seasonality controls, and compliance/privacy considerations. It is commonly asked in analytics and experimentation interviews because it tests both practical application and conceptual understanding of field experiment planning, real-world data challenges (missing outcomes, claim lag), and analysis decisions (ITT vs per-protocol, multiple testing) within the Analytics & Experimentation domain.

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CVS Health logo
CVS Health
Oct 13, 2025, 9:49 PM
Data Scientist
Technical Screen
Analytics & Experimentation
1
0

End-to-End Experiment Design: Email Campaign to Increase Verified Flu Vaccinations

Context: You are designing a 30-day email campaign to increase verified flu vaccinations among eligible health-plan/pharmacy members. Assume eligibility is: age ≥18, no verified flu shot this season, valid email and marketing opt-in, and reachable within the service area. The goal is to measure verified vaccinations (claims/EHR/pharmacy) within 30 days of first exposure.

Specify the following:

  1. Targeting and Exclusions
    • Define who is in-scope and who must be excluded (e.g., recent vaccination, bounced email, legal/marketing opt-outs, high-contact risk).
  2. Randomization Unit and Interference
    • Choose the randomization unit (individual vs household vs clinic). Explain why, and how you will limit spillover/interference across units.
  3. Holdout Structure and Seeding
    • Choose A/A, A/B, or multi-arm. Describe any pre-launch A/A checks, roll-out seeding/ramping, and how you will keep assignments stable.
  4. Metrics and Outcome Sourcing
    • Define the primary success metric and guardrail metrics. Explain how you will obtain ground truth (claims/EHR, pharmacy feeds) and handle missing outcomes for shots outside the network and claim lag.
  5. Power and Sample Size
    • Baseline 30-day vaccination rate: 2.0%; expected relative uplift: 20% (i.e., 2.4% in treatment). Use two-sided alpha=0.05 and power=0.80. Provide required sample size (equal allocation) and discuss an option for unequal allocation.
  6. Cadence, Frequency Capping, and MVT
    • Propose send cadence and frequency caps. Describe how to run multivariate subject-line/creative tests without contaminating the main treatment-control comparison.
  7. Seasonality and Overlapping Campaigns
    • Describe controls for holidays/seasonality and how you will handle other overlapping member campaigns.
  8. Compliance/Privacy
    • Address compliance constraints (opt-outs, HIPAA/PHI, content restrictions) and analytical implications.
  9. Analysis Plan
    • Specify intention-to-treat (ITT) vs per-protocol, heterogeneity reads (pre-specified subgroups), multiple testing controls, and a backstop causal method if randomization is partially broken.

Solution

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