Last edited: 1 Mar, 2023
Even though the division of traffic between Price Genius and Benchmark samples is fully random (based on the Math.random JavaScript function), the split is never exactly equal each day — especially when comparing numbers with several decimal places.
When combined with the fact that rCPMs vary from day to day, taking the average rCPM of the entire Price Genius traffic and comparing it with Benchmark can produce incorrect uplift results. The result may be either higher or lower than the actual value — there is no predictable direction.
To help you understand this, we have prepared a simple Excel simulator:
PriceGenius - uplift calculation simulator.xlsx
The detailed explanation of this phenomenon is written directly in the file.