How does AdWords data-driven attribution give credit for conversions?
It uses the linear model to credit conversions equally across all clicks on the path.
It gives 40 percent credit to the first click and spreads the remaining 60 percent across all other clicks in the conversion path.
It uses your unique account data and machine learning technology to distribute credit between ad clicks according to which touchpoints were most critical to the conversion.
It gives more credit to clicks that happened closer to the conversion.
Unlike standard position- or rules-based attribution models, Data-Driven Attribution uses actual data from your Analytics account to generate a custom model for assigning conversion credit to marketing touchpoints throughout the entire customer journey.
Read more here: https://support.google.com/analytics/answer/3264076