You are given an offline take-home style project before an onsite interview. You must analyze an A/B test and present your findings in slides.
Assume you receive a user-level dataset experiment_events with:
-
user_id
(string)
-
variant
(string; 'control' or 'treatment')
-
assignment_ts
(timestamp, UTC)
-
country
(string)
-
platform
(string; 'ios', 'android', 'web')
-
exposed
(boolean; whether the user actually saw the new experience)
-
orders_7d
(int; orders within 7 days after assignment)
-
revenue_7d
(float; revenue within 7 days after assignment)
-
support_tickets_7d
(int)
-
is_new_user
(boolean)
You also have pre-period covariates in user_pre_period:
-
user_id
-
orders_28d_pre
(int)
-
revenue_28d_pre
(float)
Tasks:
-
Define the primary metric and guardrails you would use to decide whether to ship.
-
Perform the core statistical analysis you would do (tests/CI) and list the sanity checks (e.g., SRM, balance).
-
Explain how you would handle noncompliance (
exposed = false
for some assigned users) and which estimand you’d report (ITT vs TOT).
-
Describe how you would check heterogeneous treatment effects (by platform, country, new vs existing users) without p-hacking.
-
Outline what your slide deck would contain and how you would communicate uncertainty and next steps to PM/Eng.