What is the most accurate method for measuring the incremental impact of Facebook ads on offline sales?

The most accurate method for measuring the incremental impact of Facebook ads on offline sales is using a combination of conversion lift testing and offline conversion tracking with matched customer data. Conversion lift testing involves dividing your target audience into two groups: a test group exposed to your Facebook ads and a control group that is not. By comparing the offline sales between these two groups, you can isolate the incremental impact of your Facebook ads on driving in-store purchases. Simultaneously, offline conversion tracking allows you to upload customer data (e.g., email addresses, phone numbers) to Facebook, which is then matched with Facebook users who have seen your ads. This allows you to directly attribute specific offline sales to Facebook ad exposure. Combining these two methods provides a comprehensive and accurate understanding of how Facebook ads are influencing offline sales, minimizing biases and accounting for other factors that may contribute to in-store purchases. For example, you might find that customers who saw your Facebook ad spent 20% more in-store compared to those who didn't, as determined by the conversion lift test, and you can attribute $10,000 in offline sales to specific Facebook ad campaigns based on the matched customer data.