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Meta·Data Scientist·Technical Phone Screen·Senior

Senior
May 2026

Summary

Product-focused DS interview at Meta centered entirely on notification quality metrics and experiment design. No coding, just a two-part case that went deeper than I expected once the follow-ups started rolling in.

Questions Asked (5)

Q1

What data would you look at to decide whether a notification is 'high-quality'? Think both immediate signals and longer-term ones, and consider how you'd segment.

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

I started with the obvious stuff: open rates, dismiss rates, mute/disable events.

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AI HintsAI Generated

Suggested Approach

Start by defining what 'high-quality' means for a notification in terms of user value and business goals, then outline immediate engagement signals and longer-term retention/well-being metrics. Emphasize segmentation by user, notification type, and context to avoid misleading aggregate conclusions.

Pro tip: Acknowledge the tension between short-term engagement and long-term user well-being; showing awareness of Meta's responsible notification design principles (e.g., avoiding clickbait) demonstrates maturity.

1. Define quality criteria

Clarify that a high-quality notification should be relevant, timely, and actionable, driving positive user outcomes without harming long-term engagement or well-being.

2. Identify immediate signals

List short-term metrics such as open rate, click-through rate, conversion rate, time-to-action, and dismissal/hide rate to gauge initial user response.

3. Identify longer-term signals

Consider metrics like retention, DAU/MAU, notification opt-out rate, user satisfaction (surveys), and downstream engagement to assess sustained impact.

4. Segment the analysis

Break down metrics by user demographics, notification type, frequency, time of day, and user tenure to uncover heterogeneous effects and avoid Simpson's paradox.

5. Synthesize and validate

Combine immediate and long-term signals into a composite quality score, and validate with A/B tests or causal inference to ensure the notification truly causes positive outcomes.

Key Points to Mention

  • Immediate metrics: open rate, CTR, conversion, dismissal rate
  • Long-term metrics: retention, opt-out rate, user satisfaction, well-being surveys
  • Segmentation dimensions: user demographics, notification type, frequency, time of day, user tenure
  • Avoiding clickbait: balancing short-term clicks with long-term trust
  • A/B testing to establish causality and measure incremental impact
  • Composite quality score or framework for holistic evaluation

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

Q2

Propose a primary success metric for notification quality, plus diagnostic metrics and guardrails. Define each one precisely.

Product Analytics & MetricsProduct Sense & Ideation
Author's notes

This is where I spent most of my time and I think it went reasonably well.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the goal of notification quality—likely to maximize user engagement without harming user experience. Propose a primary success metric that directly measures the value users get from notifications, then define diagnostic metrics to understand drivers and guardrails to prevent negative side effects. Ensure each metric is precisely defined with clear formulas and data sources.

Pro tip: Anchor your primary metric to a long-term user value, such as meaningful engagement or retention, rather than short-term clicks. This shows product sense and avoids optimizing for vanity metrics that could harm the user experience.

1. Clarify the objective

Confirm that the goal is to improve notification quality, balancing user engagement and user experience. Ask if there are specific constraints or focus areas (e.g., reducing opt-outs).

2. Define the primary success metric

Propose a metric like 'Notification-Attributed Daily Active Users (DAU)' or 'Notification-Driven Meaningful Sessions per User'. Define it precisely: e.g., number of users who engage with a notification and then complete a core action within a session, divided by total notified users.

3. Define diagnostic metrics

List metrics that explain the primary metric, such as click-through rate (CTR), conversion rate post-click, and time-to-action. Define each with clear formulas and data sources.

4. Define guardrail metrics

Identify metrics that ensure no harm, such as notification opt-out rate, user-reported spam rate, and app uninstall rate. Define thresholds or acceptable ranges.

5. Summarize and prioritize

Recap the metrics, emphasizing how they work together. Suggest how to monitor them and iterate on notification strategies.

Key Points to Mention

  • Primary metric should reflect long-term user value, not just short-term clicks.
  • Diagnostic metrics help identify why the primary metric changes (e.g., CTR, conversion).
  • Guardrails prevent negative outcomes (e.g., opt-outs, uninstalls, spam reports).
  • Precise definitions include numerator, denominator, time window, and data source.
  • Consider segmenting metrics by notification type, user cohort, or frequency.
  • Balance trade-offs between engagement and user experience.

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

Q3

Design an experiment to evaluate a new geographic notification feature (e.g. 'A concert is happening near you tonight'). Cover treatment vs control, randomization unit, and how long you'd run it.

A/B Testing & ExperimentationProduct Analytics & Metrics
Author's notes

Randomized at user level, treatment gets geo notifications, control gets none.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the feature's goal and defining a primary success metric (e.g., notification click-through or event attendance). Then outline a randomized controlled experiment, specifying the randomization unit (likely user-level), treatment vs. control conditions, and duration based on power analysis and novelty effects. Finally, discuss potential pitfalls like network effects and guardrail metrics.

Pro tip: Mention that you'd randomize at the user level but also consider cluster randomization if there are social spillovers, and always run an A/A test beforehand to validate the randomization.

1. Define hypothesis and metrics

State a clear hypothesis (e.g., geographic notifications increase event attendance) and choose primary (e.g., click-through rate) and guardrail metrics (e.g., notification opt-outs).

2. Design treatment and control

Treatment group receives the new geographic notification; control group receives either no notification or the existing notification (if any). Ensure both groups are otherwise identical.

3. Choose randomization unit

Randomize at the user level to avoid contamination, but consider cluster randomization (e.g., by city) if social or geographic spillovers are likely.

4. Determine sample size and duration

Calculate required sample size using power analysis (80% power, 5% significance). Run for at least one full week to capture weekly patterns, and extend if novelty effects are suspected.

5. Analyze and iterate

Compare metrics between groups using appropriate statistical tests, check for novelty effects, and decide whether to launch, iterate, or abandon based on results and guardrails.

Key Points to Mention

  • Randomization unit: user-level vs. cluster-level (e.g., city) and trade-offs
  • Primary metric: click-through rate or event attendance; guardrail metrics: notification opt-outs, user engagement
  • Sample size calculation and power analysis to determine duration
  • Novelty effect and how to detect it (e.g., by analyzing early vs. late periods)
  • Network effects and spillover: potential contamination if users interact
  • A/A test to validate randomization and instrumentation

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

Q4

What are the main threats to validity in this geo notification experiment, and how would you address them?

A/B Testing & ExperimentationAdaptability & Ambiguity
Author's notes

Covered novelty effects, seasonality, and the location-sharing selection bias.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the experiment's design and metrics, then systematically categorize threats into internal, external, construct, and statistical validity. For each threat, propose concrete mitigation strategies, emphasizing practical trade-offs and how you would validate assumptions.

Pro tip: Demonstrate awareness that geo experiments often violate independence due to spillover effects, and mention techniques like synthetic control or switchback designs as alternatives. Also, highlight the importance of pre-registering analysis plans to avoid p-hacking.

1. Clarify experiment context

Ask questions to understand the geo notification experiment: what is the intervention, how are geos assigned, what metrics are used, and what is the duration? This ensures you address the right validity concerns.

2. Categorize validity threats

Systematically go through internal (e.g., confounding, selection bias), external (e.g., generalizability), construct (e.g., metric validity), and statistical (e.g., power, multiple testing) validity threats relevant to geo experiments.

3. Propose mitigation strategies

For each threat, suggest specific solutions such as randomization checks, matching, difference-in-differences, spillover adjustments, or robust statistical methods.

4. Discuss trade-offs and validation

Acknowledge limitations of mitigations and how you would validate assumptions (e.g., placebo tests, sensitivity analyses). Emphasize iterative learning and adaptability.

Key Points to Mention

  • Spillover effects and interference between geos (e.g., users traveling across geos)
  • Selection bias and confounding due to non-random geo assignment
  • External validity: generalizing results to other regions or times
  • Statistical power and multiple comparisons when analyzing many geos
  • Construct validity: ensuring notification exposure and engagement metrics measure intended concepts
  • Use of quasi-experimental methods like synthetic control or switchback designs when randomization is limited

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

Q5

Short-term engagement goes up but opt-outs and mutes also increase. What do you conclude and what do you recommend?

Product Analytics & MetricsProduct StrategyA/B Testing & Experimentation
Author's notes

Classic disagreeing metrics scenario.

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AI HintsAI Generated

Suggested Approach

Start by acknowledging the mixed results and framing the trade-off between short-term engagement and user experience. Then, systematically break down the metrics, hypothesize potential causes, and recommend next steps such as deeper analysis or experiment iteration. Emphasize the importance of long-term user value and overall ecosystem health.

Pro tip: Highlight that opt-outs and mutes are strong negative signals that can erode long-term engagement and trust. Suggest analyzing whether the increase in short-term engagement is driven by a small segment of users, which might mask broader dissatisfaction.

1. Clarify the metrics and context

Define what 'short-term engagement', 'opt-outs', and 'mutes' mean in this context. Consider the timeframe, user segments, and any recent changes that might have triggered these shifts.

2. Analyze the trade-off

Assess whether the increase in engagement is worth the rise in negative signals. Quantify the impact: e.g., how many users are opting out relative to the engagement lift, and whether the engagement is concentrated in a small group.

3. Form hypotheses

Generate possible explanations: e.g., the change might be too aggressive, irrelevant, or spammy for some users. Consider if it's a novelty effect or if it's harming user experience.

4. Recommend next steps

Propose actions like segmenting users to identify who is opting out, running follow-up experiments with variations, or implementing safeguards to reduce negative signals while preserving engagement.

5. Evaluate long-term impact

Emphasize the need to monitor long-term metrics such as retention, user satisfaction, and overall ecosystem health. Suggest holding the change or iterating based on further data.

Key Points to Mention

  • Distinguish between short-term and long-term engagement metrics.
  • Consider user segments: are opt-outs concentrated in a particular group?
  • Evaluate the severity of opt-outs and mutes as negative signals.
  • Check for novelty effects and whether engagement is sustainable.
  • Recommend A/B testing variations to find a better balance.
  • Highlight the importance of overall user experience and trust.

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