How should the buyer/planner forecast final total spend for a campaign that is currently live and will end in 8 months?

The best approach to forecast the final total spend for a live campaign that has 8 months remaining is to calculate the average daily spend based on the last 30 days and multiply that by the number of days still in flight, then add the budget that has already been spent. This method (option A) considers the most recent performance of the campaign, allowing for a more accurate projection that reflects any fluctuations or trends in spending.

By using the average daily spend over the past month, the buyer or planner captures any variances in spending that might be occurring. This is particularly useful in digital media buying, where campaign performance can change based on market conditions, targeting efficiency, and creative effectiveness.

For instance, if there was a recent increase in spend due to a spike in performance (perhaps due to seasonal effects or a successful new creative), this method ensures that those trends are taken into account for the remaining duration of the campaign. The overall total is then adjusted by adding the amount that has already been spent to arrive at a complete picture of what the final expenditure will be.

Relying solely on historical data (as stated in option B) does not account for the current state and recent performance of the campaign, which may differ significantly from past behaviors.