What We Measure
We build the proof in GA4 before and after every change. We read your cart and checkout as two funnels, add_to_cart → begin_checkout → purchase and begin_checkout → add_payment_info → purchase, so we can see exactly where shoppers leave, then segment by device, payment type and new-versus-returning customer. The primary metrics are checkout completion rate and revenue per visitor, with guardrails on average order value, failed-payment rate and refunds, so a "win" has to survive the cuts and not quietly cost you elsewhere. Where traffic allows, we confirm the result with a controlled test rather than a before-and-after read.