An attribution model is the rule that decides how credit for a sale is divided among the marketing touches that preceded it. Common models include first-touch, last-touch, linear, and time-decay. The model you choose changes which channels appear to perform, because each one distributes credit differently.

The attribution model is a choice, not a fact, and whoever picks it quietly decides which channels look like winners. Two reports on identical data can recommend opposite budget decisions. Before you act on a channel report, ask which model produced it. If nobody can tell you, the report is an opinion wearing a number.

Example:

A deal touched by a podcast, then an ad, then an email gets credited entirely to the podcast under first-touch, entirely to the email under last-touch, and split three ways under linear.

Which attribution model is most accurate?

None is fully accurate. Each embeds assumptions about how credit should flow. The useful approach is knowing which model produced a report and reading it directionally.

Why does the attribution model change budget decisions?

Different models credit different touches, so the same data can make a channel look essential under one model and worthless under another.