Calculate Response Rate and Compare New vs. Existing User Scores

Q: How do I practice SQL interview questions?

PracHub provides an interactive SQL console where you can write and test queries against real database schemas. Get instant feedback and compare your solution with the expected output.

Q: What difficulty level is this coding question?

This is a Medium difficulty Data Manipulation (SQL/Python) question, commonly asked during Technical Screen rounds at Meta.

Q: What role is this question designed for?

This question is commonly asked for Data Scientist candidates at Meta during technical interviews.

Question

survey_events

+---------+------------+-----------+--------------+---------------------+
| user_id | is_new_user| responded | survey_score | event_time          |
+---------+------------+-----------+--------------+---------------------+
| 101     | true       | true      | 5            | 2023-11-01 10:00:00 |
| 102     | false      | false     | NULL         | 2023-11-01 10:05:00 |
| 103     | true       | true      | 4            | 2023-11-01 10:10:00 |
| 104     | false      | true      | 3            | 2023-11-01 10:20:00 |
| 105     | true       | false     | NULL         | 2023-11-01 10:30:00 |
+---------+------------+-----------+--------------+---------------------+

##### Scenario

Product team ran an in-app survey and stored results in a table; they need response rate and to know if new users provide better survey scores.

##### Question

Write SQL to calculate the overall survey response rate. Write SQL to compare average survey_score between new and existing users and test if the difference is significant.

##### Hints

Use conditional aggregation or CTEs; remember NULL handling.

PracHub · Accepted Answer

This question evaluates data manipulation and statistical analysis skills for a data scientist, focusing on SQL aggregation, NULL handling, cohort comparison, and testing differences in survey scores.

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