Detect Sudden Reviewer Accuracy Drops | Dataford Interview Questions

You are given review outcomes for a set of reviewers. Write a PostgreSQL query that flags the first day each reviewer’s accuracy drops by at least 20 percentage points compared with the previous review day, and returns the reviewer, the date of the drop, the prior day’s accuracy, the current day’s accuracy, and the size of the drop.

Use only the data in the table below. Treat accuracy as correct_reviews / total_reviews, and ignore rows where total_reviews = 0 when calculating accuracy. Return one row per reviewer for the first qualifying drop, ordered by the largest drop first.

Schema

reviewer_daily_stats

Column	Type	Description
reviewer_id	INT	Reviewer identifier
reviewer_name	VARCHAR(100)	Reviewer display name
review_date	DATE	Date of the review batch
correct_reviews	INT	Number of correct reviews on that day
total_reviews	INT	Total reviews completed that day

Your question is Detect Sudden Reviewer Accuracy Drops. Start with the requirements and the one table in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem

Schema

reviewer_daily_stats

Column	Type	Description
reviewer_id	INT	Reviewer identifier
reviewer_name	VARCHAR(100)	Reviewer display name
review_date	DATE	Date of the review batch
correct_reviews	INT	Number of correct reviews on that day
total_reviews	INT	Total reviews completed that day

Your question is Detect Sudden Reviewer Accuracy Drops. Start with the requirements and the one table in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.