問題文
A cohort analysis shows that customers acquired in March retain far better than those acquired in April. Before concluding that the March campaign was better, what must be checked?
選択肢
- Whether the two cohorts have the same number of customers, since retention rates are not comparable across different cohort sizes, and the size drives the rate.
- Whether both cohorts are stored in the same table, since cross-table comparisons introduce definition drift.
- Whether the campaign used the same creative in both months, since retention is determined by the acquisition message.
- Whether the two cohorts have been observed for the same length of time, since a younger cohort has had fewer chances to churn or return.