Topic
Every post on the Index about budget planning.
Jeff says revenue per session, such as the gap between paid ChatGPT and paid Google Search, improves on click volume. It still counts buyers who would have purchased anyway, so budgets should rest on incremental revenue per dollar instead.
Jeff reads Expedia's CEO comment that AI agents haven't changed bookings as a sign they are one more funnel input, like Google or Reddit. Measurement gaps are normal, and claims of a perfect picture deserve suspicion when setting budgets.
Jeff uses record campaign spending that didn't deliver votes to argue that spend isn't impact, since much of it reaches people who had already decided. Brands face the same problem, because publisher-reported credit and last click can't separate changed behavior from counted conversions.
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