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Coinbase·Data Scientist·Technical Phone Screen·Senior

SeniorPrefer not to say
Jul 2026Remote

Summary

Coinbase data science interview with a product analytics case built around a Super Bowl QR code campaign. The whole thing was funnel estimation, which sounds straightforward until you're actually in it trying to justify every assumption out loud.

Questions Asked (4)

Q1

Given a TV network airs a QR code ad during the Super Bowl, how would you estimate the percentage of viewers who actually scan the code?

Product Analytics & MetricsAdaptability & Ambiguity
Author's notes

I went straight to viewership numbers and tried to layer in attention decay, second-screen behavior, that kind of thing.

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AI HintsAI Generated

Suggested Approach

Break the problem into a funnel: total Super Bowl viewers → those who noticed the ad → those who have the app/ability to scan → those who actually scan. Use a mix of known benchmarks (e.g., Super Bowl viewership, ad recall rates, QR scan rates) and reasonable assumptions to estimate each stage, then multiply to get a percentage. Sanity-check the final number against real-world examples (e.g., Coinbase's 2022 QR code ad) and discuss sources of uncertainty.

Pro tip: Anchor your estimate to a known real-world event (like Coinbase's 2022 Super Bowl ad) and use it to validate your assumptions; this shows you can connect theory to practice and understand the business context.

1. Define the target population

Start with the total number of Super Bowl viewers (e.g., ~100 million in the US) and consider segmentation (e.g., live vs. streaming, domestic vs. international).

2. Estimate ad exposure and attention

Determine what fraction of viewers actually saw the ad (e.g., not all watch ads; some may leave the room) and paid attention to it (ad recall rates).

3. Assess ability and intent to scan

Estimate the percentage of viewers who have a smartphone with a QR scanner, are Coinbase users or interested, and are motivated to scan immediately.

4. Apply a scan conversion rate

Use benchmarks for QR code scan rates from TV ads (often low, e.g., 0.1-1%) or analogous digital campaigns to estimate the final conversion.

5. Calculate and sanity-check

Multiply the fractions to get an overall percentage, then compare with real-world data (e.g., Coinbase reported ~20 million scans from their 2022 ad) to validate or adjust.

Key Points to Mention

  • Super Bowl viewership numbers (e.g., ~100 million viewers)
  • Ad recall and attention rates for Super Bowl ads
  • QR code scan rates from TV or digital ads (typically low, <1%)
  • Smartphone penetration and QR scanning capability
  • Coinbase's 2022 Super Bowl QR code ad results (~20 million scans)
  • Sources of uncertainty and how to communicate them

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.

Q2

What data sources would you draw on to support this kind of scan rate estimate?

Product Analytics & MetricsRoot Cause Analysis
Author's notes

Pretty open-ended.

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AI HintsAI Generated

Suggested Approach

Start by clarifying what 'scan rate' means in this context—likely the rate at which users scan QR codes for payments or wallet interactions—and then outline a layered data strategy. Emphasize combining internal product telemetry (e.g., event logs, transaction data) with external market data and experimentation results to triangulate the estimate. Structure your answer around data source categories, validation methods, and potential biases.

Pro tip: Demonstrate awareness of Coinbase's data ecosystem by mentioning specific internal sources like the event stream from the mobile app, on-chain data for wallet scans, and A/B test results—showing you understand both product analytics and crypto-specific nuances.

1. Clarify the metric and context

Define 'scan rate' precisely: is it scans per user, per session, or per transaction? Identify the product surface (e.g., QR code payments, wallet address scanning) and the time window.

2. Identify internal product data sources

List sources like mobile/web event logs (e.g., button clicks, camera opens), transaction records, user session data, and backend service logs that capture scan events.

3. Incorporate external and third-party data

Consider market research, industry benchmarks, app store analytics, and on-chain data (for wallet scans) to supplement internal data and fill gaps.

4. Leverage experiments and surveys

Use A/B test results, feature flag data, and user surveys to validate scan behavior and understand intent behind scans.

5. Validate and triangulate

Cross-check estimates from different sources, assess data quality (e.g., sampling bias, logging gaps), and reconcile discrepancies to produce a robust estimate.

Key Points to Mention

  • Event-level telemetry from mobile and web apps (e.g., scan button clicks, camera permissions, successful scans)
  • Transaction and payment logs that record scan-based interactions
  • On-chain data for wallet address scans or QR code payments in crypto
  • A/B test and experimentation platforms to measure causal impact of features on scan rates
  • User surveys or feedback to capture off-platform scans and intent
  • External benchmarks from industry reports or competitor analysis

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.

Q3

If you only have prior TV campaign data and no ad-partner conversion data, how do you approximate the scan rate?

Product Analytics & MetricsA/B Testing & Experimentation
Author's notes

This is where I fumbled a bit.

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AI HintsAI Generated

Suggested Approach

Start by acknowledging the data limitation and proposing a triangulation approach that combines TV campaign metrics with external benchmarks and statistical modeling. Use techniques like media mix modeling (MMM) or Bayesian inference to estimate scan rates, leveraging proxies such as website traffic or app downloads. Emphasize validation and sensitivity analysis to ensure robustness.

Pro tip: Leverage industry benchmarks for QR/scan rates from similar campaigns or platforms, but adjust for Coinbase's unique audience and campaign context. Clearly state assumptions and propose a pilot test to calibrate the model, showing you balance pragmatism with rigor.

1. Define the Objective and Constraints

Clarify what 'scan rate' means (e.g., scans per impression) and acknowledge the missing ad-partner conversion data. Identify available TV campaign data (impressions, GRPs, reach) and any other internal data (website visits, app installs).

2. Identify Proxies and Benchmarks

Use external benchmarks for scan rates from similar industries or QR code campaigns. Consider internal proxies like direct traffic spikes or branded search volume that correlate with scans.

3. Model the Relationship

Apply media mix modeling (MMM) or regression techniques to link TV exposure to proxy metrics. Use Bayesian methods to incorporate prior knowledge and quantify uncertainty.

4. Estimate Scan Rate and Validate

Derive an approximate scan rate from the model, then validate via sensitivity analysis and, if possible, a small-scale pilot or holdout test to calibrate.

5. Communicate Assumptions and Limitations

Present the estimate with confidence intervals and clearly state assumptions. Recommend next steps to collect better data, such as implementing unique QR codes or partnering with ad platforms.

Key Points to Mention

  • Media mix modeling (MMM) to attribute TV impact
  • Bayesian inference for incorporating prior benchmarks
  • Use of proxies like website traffic or app downloads
  • Sensitivity analysis to test robustness of assumptions
  • Industry benchmarks for QR/scan rates
  • Proposal for a pilot test to calibrate the model

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.

Q4

How would you estimate the conversion rate from someone scanning the QR code to completing an account sign-up?

Product Analytics & MetricsProduct Sense & Ideation
Author's notes

Felt more comfortable here.

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AI HintsAI Generated

Suggested Approach

Break down the funnel into distinct stages (QR scan → landing page → sign-up start → completion) and estimate conversion at each stage using benchmarks, assumptions, and available data. Then combine these estimates to get an overall conversion rate, while acknowledging uncertainties and suggesting ways to validate with real data.

Pro tip: Emphasize that the estimate should be actionable: identify which stage has the lowest conversion and propose experiments to improve it, showing you think beyond just the number.

1. Define the funnel stages

Map out the user journey from scanning the QR code to completing sign-up, including intermediate steps like landing on a webpage, starting the sign-up form, and submitting it.

2. Gather data and benchmarks

Use internal data if available (e.g., from similar campaigns) or industry benchmarks for each stage, such as QR scan-to-landing page conversion, landing page-to-sign-up start, and sign-up completion rates.

3. Estimate stage-wise conversion rates

Assign reasonable conversion rates for each stage based on data or assumptions, considering factors like user intent, friction, and device type.

4. Calculate overall conversion rate

Multiply the stage-wise conversion rates to get the overall conversion rate from QR scan to completed sign-up.

5. Validate and refine

Suggest methods to validate the estimate, such as A/B testing, tracking actual funnel data, or using probabilistic models to account for uncertainty.

Key Points to Mention

  • Funnel decomposition: breaking down the process into measurable stages.
  • Use of internal data (e.g., past QR campaigns) and external benchmarks.
  • Consideration of user intent and context (e.g., scanning from a mobile device).
  • Impact of friction points (e.g., form length, KYC requirements for Coinbase).
  • Quantification of uncertainty and sensitivity analysis.
  • Actionable insights: identifying drop-off points and suggesting improvements.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.