A metric is not event based. You don't have a metric 'person logged in' because you would need to scrape the metric at the moment a person logged in. You have

A metric is not event based. You don't have a metric 'person logged in' because you would need to scrape the metric at the moment a person logged in. You have a metric called 'overall people have logged in so far' and you do math on it. The 'person logged in' is an event you log out.