How compare Waymo turning trajectories statistically

Quick Overview

This question evaluates statistical inference and trajectory-analysis competencies, including representation of 2D turning paths, time-series feature extraction, and comparative modeling to detect behavioral differences between an autonomous fleet and other road users.

How compare Waymo turning trajectories statistically

Company: Waymo

Role: Data Scientist

Category: Statistics & Math

Difficulty: easy

Interview Round: Technical Screen

## Problem You have aerial-drone data that records the **2D turning trajectories** of vehicles passing through multiple intersections. Each trajectory corresponds to one vehicle executing a turn (e.g., left or right) within an intersection. Some trajectories are from **Waymo autonomous vehicles**, and the rest are from **other vehicles** (human-driven and/or other fleets). You want to quantify whether **Waymo’s turning behavior differs** from the population of all other vehicles. ### Data (assume) Each observed turn is a trajectory with timestamps: - `intersection_id` - `vehicle_type` (Waymo vs Other) - `turn_type` (left/right/straight, if available) - `t` (time) - `x(t), y(t)` (position in a local intersection coordinate frame) Optionally derived signals (from smoothing/finite differences): - speed `v(t)`, heading `θ(t)`, curvature `κ(t)`, acceleration `a(t)` ### Tasks 1. **Define a statistical approach** to test/quantify whether Waymo trajectories differ from other vehicles. - What trajectory representation / features would you use? - What distributional assumptions (if any) would you make? - What hypothesis test or model would you use? - What effect size would you report? 2. **Follow-up (traffic volume differs by intersection):** Intersections have different traffic volumes and potentially different driving patterns. - How would you adjust your analysis so differences aren’t confounded by intersection-level factors (including traffic volume)? - What model or design would you use to compare Waymo vs Other fairly across intersections? State key assumptions, pitfalls, and how you’d validate them.

Quick Answer: This question evaluates statistical inference and trajectory-analysis competencies, including representation of 2D turning paths, time-series feature extraction, and comparative modeling to detect behavioral differences between an autonomous fleet and other road users.

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Feb 7, 2026, 1:57 AM
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Problem

You have aerial-drone data that records the 2D turning trajectories of vehicles passing through multiple intersections. Each trajectory corresponds to one vehicle executing a turn (e.g., left or right) within an intersection.

Some trajectories are from Waymo autonomous vehicles, and the rest are from other vehicles (human-driven and/or other fleets). You want to quantify whether Waymo’s turning behavior differs from the population of all other vehicles.

Data (assume)

Each observed turn is a trajectory with timestamps:

  • intersection_id
  • vehicle_type (Waymo vs Other)
  • turn_type (left/right/straight, if available)
  • t (time)
  • x(t), y(t) (position in a local intersection coordinate frame) Optionally derived signals (from smoothing/finite differences):
  • speed v(t) , heading θ(t) , curvature κ(t) , acceleration a(t)

Tasks

  1. Define a statistical approach to test/quantify whether Waymo trajectories differ from other vehicles.
    • What trajectory representation / features would you use?
    • What distributional assumptions (if any) would you make?
    • What hypothesis test or model would you use?
    • What effect size would you report?
  2. Follow-up (traffic volume differs by intersection): Intersections have different traffic volumes and potentially different driving patterns.
    • How would you adjust your analysis so differences aren’t confounded by intersection-level factors (including traffic volume)?
    • What model or design would you use to compare Waymo vs Other fairly across intersections?

State key assumptions, pitfalls, and how you’d validate them.

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