An average that means nothing

AVERAGE does not ask what the numbers represent. Point it at a column of year groups, room numbers or satisfaction codes and it returns a figure with decimal places and complete confidence.

The guard is yours, not Excel's: average ratio and interval data, never nominal, and think hard before averaging ordinal. A mean rating of 2.7 on a four-point scale is a number nobody can act on, because the gap between Fair and Good is not the same size as the gap between Good and Excellent.