Hi everyone. Got confused a little bit when adding an idea to Growthbook. I really dig I have a chance to pre-calculate the sample size for an experiment, but here’s where I got confused. I chose a metric and user segment to calculate the sample size, but in the metric settings I have a conversion delay of 24 hours and conversion window of 48 hours, so I expected it to be reflected in the underlying query, but it doesn’t look it is. I expected the “conversion start” and “conversion end” to add 24 and 48 hours respectively.

__metric as ( -- Metric (Retention [1st Day][GA])
    SELECT
      user_id as user_id,
      1 as value,
      CAST(m.timestamp as DATETIME) as timestamp,
      CAST(m.timestamp as DATETIME) as conversion_start,
      CAST(m.timestamp as DATETIME) as conversion_end
    FROM
      (
        SELECT
          CAST(user_id AS INT64) AS user_id,
          1 AS value,
          created_at AS timestamp
        FROM
          `normalized.events`
        WHERE
          event_name = "page_view"
          AND DATE(created_at) >= '2022-09-01'
      )

In order to use conversion windows, we need an "activation" event. In an actual experiment it's easy - we just use the date the person sees the experiment. When it's just an idea, we don't have an activation event, so we just ignore the conversion windows in our calculations. I think that's something we might be able to improve though. We could in theory let you specify a custom activation event (e.g. "viewed checkout page") and use that when looking up metric conversions.

This seems like a way to go. But the expected behavior I had in mind was that the activation event was actually the date the user was added to the segment. Say, I want to estimate the sample size for a planned experiment on the pricing page of our website. I can create a segment and named it “Viewed Pricing Page”, where the page_view date is the date the user was added to the segment.

Hi @some-planet-44104 🙂 I was wandering also about the date field, did you mange to set it up? Should it be the date the user was added to the segment?