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Lyft·Data Scientist·Technical Phone Screen·Intermediate

Intermediate
Jun 2026

Summary

Lyft data science interview with a probability/Markov chain question built around their dynamic pricing feature. The setup was clever and felt more applied than the usual brain teaser, but it still required you to actually know your probability fundamentals under pressure.

Questions Asked (1)

Q1

Lyft is running a dynamic pricing trial. A rider takes two rides on day one, and each ride has probability P of being priced reasonably. Based on their day-one experience, what is the probability they take exactly one ride the next day? And what is the probability they become a permanent daily rider?

A/B Testing & ExperimentationPricing & MonetizationProduct Analytics & Metrics
Author's notes

The setup took me a minute to parse.

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AI HintsAI Generated

Suggested Approach

Start by clarifying that the question is underspecified and requires assumptions about how day-one experience affects future ride behavior. Propose a simple probabilistic model, such as a Markov chain, where the probability of taking a ride the next day depends on whether the rider had a good or bad experience on day one. Then compute the requested probabilities under that model, and discuss how you would validate or refine the model with real data.

Pro tip: Explicitly state your assumptions and note that in a real analysis you would estimate these transition probabilities from experimental data rather than assume them. This shows you understand the difference between a theoretical exercise and practical data science.

1. Clarify the problem and assumptions

Identify that the question lacks details on how day-one experience influences future behavior. Assume each ride independently has probability P of being priced reasonably, and define how this affects the rider's likelihood to take future rides.

2. Define a behavioral model

Propose a model where the rider's probability of taking a ride on day two depends on the number of reasonably priced rides on day one. For example, let q_k be the probability of taking a ride on day two given k good experiences on day one.

3. Compute day-one experience probabilities

Calculate the probability of having 0, 1, or 2 reasonably priced rides on day one using the binomial distribution with parameters n=2 and probability P.

4. Calculate the probability of exactly one ride on day two

Use the law of total probability: sum over k=0,1,2 of P(k good rides on day one) * P(take exactly one ride on day two | k good rides). If the rider takes at most one ride per day, then this is simply the probability they take a ride on day two.

5. Calculate the probability of becoming a permanent daily rider

Define 'permanent daily rider' as taking a ride every day from day two onward. If the daily decision is independent given the day-one experience, this probability is the product of daily ride probabilities from day two onward, which may be zero unless the daily probability is 1. Alternatively, model it as an absorbing state in a Markov chain.

Key Points to Mention

  • Binomial distribution for day-one outcomes
  • Law of total probability
  • Markov chain or state transition model
  • Assumptions about independence and stationarity
  • Need for empirical estimation of transition probabilities
  • Definition of 'permanent daily rider' and how it affects the calculation

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