Campaign Measurement, Reporting, and Analytics
Measurement turns spend into decisions. Candidates must know the core metrics and how they relate: impressions, clicks, click-through rate (CTR = clicks ÷ impressions), cost-per-click (CPC = spend ÷ clicks), conversion rate (CVR = orders ÷ clicks), cost per acquisition (CPA = spend ÷ orders), ACOS (spend ÷ ad sales), ROAS (ad sales ÷ spend, the inverse of ACOS), and total ACOS (TACOS = total ad spend ÷ total sales). Attribution windows matter - Amazon ad reports typically attribute sales within a defined window after a click, so short-window reports understate longer consideration cycles. New-to-brand metrics separate new customers from repeat buyers.
Traps: comparing ACOS and ROAS as if they were the same number, reading a single day's data as a trend, ignoring attribution-window differences, treating ad-attributed sales as total incremental sales, and forgetting that organic and ad sales interact. Also watch for confusing TACOS (ad spend against all sales) with ACOS (ad spend against ad sales only).
Rule of thumb: diagnose top-down - impressions (are you visible?), CTR (is the offer relevant?), CVR (does the listing convert?), then ACOS/ROAS (is it efficient?). Worked example: 100,000 impressions, 500 clicks, 25 orders, $500 spend, $1,250 ad sales. CTR = 0.5%, CPC = $1.00, CVR = 5%, ACOS = 40%, ROAS = 2.5. If total sales are $5,000, TACOS = 10% - a healthy blended figure even though the campaign ACOS is high.