Why this is mistaken
Ask what one row represents, then name the fields recorded about it. In the
Juniper packet, the invoice is the unit, days_to_settlement is a variable, and
31 days is one value. A repeated invoice key is a grain or duplicate question,
not another variable.
Where to watch
When this mistake may appear
- A table contains several columns and repeated business identifiers.
- A join creates more than one row for one invoice or security.
Check your work
Your work may contain this mistake if:
- Calls days_to_settlement the observational unit.
- Counts joined payment rows as independent invoices without checking grain.