Data Analysis & BI Interview Questions and Answers

Vanity metrics look impressive but do not guide decisions: total registered users, page views, cumulative downloads. They only go up, lack context and cannot be tied to a specific action.

Actionable metrics are tied to a behaviour you can influence and have a clear link to value: activation rate, weekly active users, conversion rate, retention, average order value. They can move up or down and prompt a response.

For example, ten million page views is vanity, while the percentage of new users who complete onboarding within 24 hours is actionable because a product change can shift it.

The test: if the metric doubled or halved, would you change what you are doing? If not, it is probably vanity. Pair metrics with segments and a time frame for context so teams focus on outcomes rather than activity.

DAU is daily active users, the number of unique users who perform a meaningful action in a day. MAU is the same over a month. The action must be defined consistently: a login may not be meaningful for a content app, while a read or post is.

Stickiness is DAU divided by MAU, the share of monthly users who return on any given day. A high ratio means frequent habitual use. Social and messaging apps often exceed 50 percent, while e-commerce is typically much lower.

SELECT COUNT(DISTINCT CASE WHEN day = current_date THEN user_id END) AS dau,
       COUNT(DISTINCT user_id) AS mau
FROM activity
WHERE day >= current_date - INTERVAL '30 days';

Watch for definitional drift and time zones, which can distort daily boundaries. Pair these with retention curves: DAU/MAU shows frequency, retention shows whether users return at all.