When planning advertising campaigns in different digital media, the results of each channel are often reported separately, which can lead to duplications in reach metrics, as the same person may see the ad on different platforms. This happens because it is common for different campaigns to reach the same people, creating redundancies in how to calculate reach effectively.
Faced with this challenge, we at Bunker chose the most accurate way to calculate net reach by avoiding counting the same person multiple times using the Sainsbury's formula.
How does the formula work? 🧪
Sainsbury's assumes that the probability of a user seeing an ad in different media can be represented in a simple way: if they see it, it is 1; if they don't see it, it is 0. Thus, when we combine several media (such as TV, internet, etc.), we calculate how many people actually saw the ad without counting duplicates.
The formula combines the reach of all media to which the user was exposed and subtracts duplications, thus: 1 - [[1-A]*[1-B]*[1-C]*[1-D]*...[1-n]]]
Where do we apply it?
The Sainsbury's formula is applied in:
In the «Analytics» module (brand) to calculate the total Reach of Google Ads in the Paid Media tables but only at the Total Campaigns level since the Google API does not provide the Reach data at the Ad Group and Ads levels.
In Paid Media for the Paid account summary at brand level. Now you can see the total Reach between media.
🚨Important: Google Ads does not provide the reach for the Search network so the network is not considered for the calculation of the Google Ads Total Reach or between media.
