Question on the “Activation Metric” option under Experiment Settings: I’ve set “Signed up” as the activation metric to only include users who signed up after being allocated to one of the variants. Is this how the activation metric works, i.e. it implicitly compares sign up date with variant allocation date?

Yes. Activation metric conversion date must be after the experiment assignment date. And any goal metric conversions must happen after the activation metric.

Got it, thanks!