statistics.compare: not enough matched pairs...

Warnings reference › compare:paired

Identifier

compare:paired

Raised by

The grid (core)

Since

1.106.0

What happened

A paired test compares the difference within matched rows, and after joining on the key field fewer than three pairs survive. There is nothing to test, so the call returns null.

The fix

Check that the key field matches enough rows across the two groups, or drop paired.

Reference

Covered in full at the API reference.