Why this is mistaken
Standard deviation describes the selected observations. Standard error
describes estimated variation in a statistic across repeated samples. For the
simple mean method, SE = s / sqrt(n); the division changes the object.
Where to watch
When this mistake may appear
- Both outputs use the same original unit.
- A report abbreviates both measures.
Check your work
Your work may contain this mistake if:
- Says standard error describes invoice-level variation.
- Uses standard deviation directly as interval half-width.