Experimentation Metrics and Strategy Questions
Designing experiments and selecting appropriate primary, secondary, and guardrail metrics to evaluate hypotheses while protecting long term user value. This includes choosing metrics that reflect both short term signal and long term outcomes, reasoning about metric interactions and potential unintended consequences, and applying statistical considerations such as minimum detectable effect, sample size and power analysis, test duration, and external validity across segments and platforms. Candidates should also discuss experiment risk mitigation, stopping rules, and how to operationalize experiment results into product decisions.
Sample Answer
Sample Answer
Sample Answer
import numpy as np
def simulate_one(p0, p1, n_per_look, bounds):
total_n = 0
for look, n in enumerate(n_per_look):
total_n = n
# simulate data up to current look
x_ctrl = np.random.binomial(n//2, p0)
x_treat = np.random.binomial(n//2, p1)
# compute z-stat
p_pool = (x_ctrl + x_treat) / n
se = np.sqrt(p_pool*(1-p_pool)*(2/(n//2)))
z = (x_treat/(n//2) - x_ctrl/(n//2)) / se
if z >= bounds['upper'][look]:
return 'efficacy', look+1
if 'lower' in bounds and z <= bounds['lower'][look]:
return 'futility', look+1
return 'none', len(n_per_look)Sample Answer
Sample Answer
-- build account-level outcomes and treatment indicator
WITH account_agg AS (
SELECT
a.account_id,
MAX(a.treatment) AS treatment, -- treatment assigned at account
COUNT(DISTINCT u.user_id) AS n_users,
SUM(e.revenue) AS total_revenue,
SUM(CASE WHEN e.event_type='purchase' THEN 1 ELSE 0 END) AS purchases,
AVG(u.signup_age_days) AS avg_signup_age
FROM accounts a
LEFT JOIN users u ON u.account_id = a.account_id
LEFT JOIN events e ON e.user_id = u.user_id
GROUP BY a.account_id
)
SELECT * FROM account_agg;-- After computing beta_hat (from external routine), compute residuals per row
WITH resid AS (
SELECT
a.account_id,
u.user_id,
y.metric AS y,
t.treatment AS t,
-- other covariates x1,x2...
(y - (b0 + b1*t + b2*x1 + ...)) AS resid
FROM users u
JOIN accounts a ON a.account_id = u.account_id
JOIN ... -- join metrics
)
-- compute per-cluster score sums
SELECT
account_id,
SUM(resid * 1) AS S_intercept,
SUM(resid * treatment) AS S_treatment,
SUM(resid * x1) AS S_x1
FROM resid
GROUP BY account_id;Unlock Full Question Bank
Get access to hundreds of Experimentation Metrics and Strategy interview questions and detailed answers.
Sign in to ContinueJoin thousands of developers preparing for their dream job.