Marketing Attribution Model Comparison

Switching from last-click to data-driven attribution in GA4 is not a measurement decision — it is a budget allocation decision. When we rebuild attribution for client accounts, the model switch almost always reveals one paid channel significantly overvalued on last-click data: usually branded search or direct, because those channels capture credit at the point of conversion rather than the point of influence. What follows is a practical breakdown of what each GA4 attribution model is actually doing, what decisions shift when the data changes, and why most teams that make the switch without changing their optimisation approach end up with better data and the same bad budget calls.

What last-click gets wrong

Last-click credits 100% of a conversion to the final touchpoint. This systematically overvalues branded search and direct traffic, and undervalues the channels that generated awareness and consideration earlier in the journey. If your paid social looks underperforming on a last-click basis, data-driven will almost always show a different picture.