It looks as in case no 2nd series is provided, the test compares to a constant series - compare with this:

<hansl>

# Compare

series y = 1

meantest gdpgrow y --paired

</>

I guess that should be mentioned in the help text or output. Alternatively, an error may be flagged as two series are expected.

What worries me here is the implicit comparison against a non-zero constant term. Comparing against zero feels natural, but why against 1?

Apart from that, I agree that the --paired option should not be allowed together with a single input.

thanks

sven