We want to test a new activation reminder text. Our current 30-day activation rate for new cards is 30%, and the business wants to be able to detect a 2-percentage-point lift. We get about 4,000 new cardholders a week, split 50/50. At 5% significance and 80% power, how many people do we need per group, and how many weeks should the test run?

我们想测一条新的激活提醒短信。现在新卡30天激活率是30%，业务希望能测出2个百分点的提升。每周大概有4000个新卡客户，对半分组。按5%显著性、80%功效，每组要多少人？实验要跑几周？