In an A B test, control shows 10,000,000 impressions with 1.20% CTR; treatment shows 10,000,000 impressions with 1.23% CTR. (a) Compute the absolute and relative lift, the pooled standard error, z statistic, and two-sided p value. Provide a 95% confidence interval for the relative lift. (b) If you peeked daily over 14 days without alpha spending, quantify approximate Type I error inflation and propose a corrected sequential plan using alpha spending or a Bayesian alternative with a prior on lift. (c) If you also track 8 guardrail metrics, explain how you would control familywise error or false discovery rate.