Finding causes.
WHERE TO START
Segment it.
A fall overall is usually a fall in one part.
WHAT TO SPLIT BY
Product, customer type, channel, region, period.
WHAT THAT NARROWS
The question, from why did revenue fall to why did this segment fall.
THEN ASK
What changed at that time?
Prices, staff, suppliers, competitors, seasons, marketing, a system change.
WHAT TO CHECK
Whether the change is in volume or in value Whether it is fewer customers or smaller purchases
THOSE ARE DIFFERENT PROBLEMS
WHAT TO RULE OUT FIRST
A data problem.
A missing export or a changed category explains many apparent changes.
WHAT TO DO WHEN DATA CANNOT ANSWER IT
Ask people. Customers, staff, suppliers.
WHAT NOT TO DO
Settle on the first plausible explanation Assume the cause you expected
WHAT TO RECORD
What you concluded and why.