The premium for behaviorally targeted (BT) ads, compared with run-of-network (RON) ads, ranges from 1.8X - 3.5X; but the increase in conversion rates from using BT ranges from 2.1X - 2.9X -- on par with the premium CPM paid for BT vs RON. So the cost per outcome stays about the same, making behavioral targeting NOT incrementally useful for marketing efficiency.

1. June 2019 / Page 0marketing.scienceconsulting group, inc.
linkedin.com/in/augustinefou
Behavioral Targeting is NOT Worth the Premium
Source: [PDF] https://www.researchgate.net/profile/Howard_Beales/publication/265266107_The_Value_of_Behavioral_Targeting/links/599eceeea6fdcc500355d5af/The-Value-of-
Behavioral-Targeting.pdf
2.4X
2.6X
2.4X
2.9X
2.1X
2.1X
2.1X
2.1X
2.2X
2.0X