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Lyft·Data Scientist·Technical Phone Screen·Intermediate

Intermediate
May 2026

Summary

Lyft data scientist interview that leaned heavily on foundational stats, the kind of stuff you think you know cold until someone asks you to explain it to a room full of non-technical stakeholders.

Questions Asked (2)

Q1

State Bayes' theorem and walk through a concrete example showing how it works.

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

I knew the formula but fumbled the intuition part.

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AI HintsAI Generated

Suggested Approach

State Bayes' theorem clearly and concisely, then walk through a concrete example that is relevant to the role, such as A/B testing or product analytics. Use the example to demonstrate how prior beliefs are updated with new evidence to produce a posterior probability.

Pro tip: Choose an example that ties directly to Lyft's business, like estimating the probability a rider is a repeat user given they took a ride during surge pricing, to show practical application. Avoid overly complex math; focus on intuition and business impact.

1. State the theorem

Write Bayes' theorem in its standard form: P(A|B) = P(B|A) * P(A) / P(B). Define each term clearly (prior, likelihood, marginal probability, posterior).

2. Set up a concrete scenario

Choose a realistic example, such as determining whether a user will churn given they had a poor ride experience. Define events A and B and assign plausible probabilities.

3. Apply the formula

Plug the numbers into Bayes' theorem, showing each step of the calculation. Explain what each component represents in the context of the example.

4. Interpret the result

Explain what the posterior probability means in business terms. Discuss how the prior was updated by the evidence and what actions might follow.

5. Connect to data science at Lyft

Briefly mention how Bayesian reasoning applies to A/B testing, product analytics, or decision-making under uncertainty at Lyft.

Key Points to Mention

  • Definition of prior, likelihood, evidence, and posterior probabilities
  • The role of Bayes' theorem in updating beliefs with new data
  • A concrete example with numbers (e.g., churn prediction, ride acceptance)
  • Interpretation of the result in business terms
  • Connection to A/B testing or product analytics
  • Avoiding common pitfalls like base rate neglect

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

Q2

Explain what a p-value actually means in plain terms, including what it does NOT tell you.

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

The 'does not tell you' part is where I stumbled.

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AI HintsAI Generated

Suggested Approach

Start by defining a p-value in intuitive terms, then clearly state what it does not mean, and finally connect it to the context of A/B testing at a company like Lyft. Use a concrete example to illustrate the concept and avoid technical jargon.

Pro tip: Emphasize that a p-value is not the probability that the null hypothesis is true, and that it must be interpreted alongside effect size and confidence intervals to make sound business decisions.

1. Define p-value simply

Explain that a p-value is the probability of observing data as extreme as (or more extreme than) what we saw, assuming the null hypothesis is true. Avoid saying it's the probability the null is true.

2. Clarify what it does NOT mean

State that it does not measure the size or importance of an effect, nor the probability that the null hypothesis is true or that results are due to chance alone.

3. Connect to A/B testing

Relate it to experimentation: a low p-value suggests the observed difference is unlikely under the null, but it doesn't guarantee practical significance. Mention the need to consider effect size and business impact.

4. Use an example

Provide a concrete example, such as testing a new feature at Lyft, to illustrate how a p-value is computed and interpreted in decision-making.

Key Points to Mention

  • p-value is the probability of observing data at least as extreme as the sample, given the null hypothesis is true
  • It is not the probability that the null hypothesis is true
  • It does not indicate the size or practical significance of an effect
  • A low p-value does not prove the alternative hypothesis; it only suggests evidence against the null
  • p-values depend on sample size and can be small for trivial effects in large samples
  • Always interpret p-values alongside effect sizes, confidence intervals, and business context

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