From: Marcus Reed, sales director at Juniper Lane
Re: Who is behind?
We set monthly revenue targets for each region (targets.csv: region, month, target). Before the board meeting I need to know which region missed its targets by the most over the last three complete months, and whether that was one bad month or a pattern.
Be careful with the data: the sales export (sales.csv, loaded as df) stops partway through June, and a region can have a month with no sales at all, which still counts against its target.
Your answer is one of four statements, backed by the numbers you build on the way.
A case study is a business question answered with analysis. You'll check how complete the data is, build monthly actuals, join them to targets without losing a month, measure the gaps, and pick the answer the numbers support.
The traps here are real ones: an incomplete last month that makes every region look bad, and a join that silently drops a month with no sales.