To allow for early feedback in a risk-managed manner, we use sequential tests to monitor regressions in the experiments. However, when moving toward smaller and smaller time windows, we’re faced with multiple measurements per unit in our analysis, which is known as longitudinal data.

Read more: https://engineering.atspotify.com/2023/07/bringing-sequential-testing-to-experiments-with-longitudinal-data-part-1-the-peeking-problem-2-0/